parts of brain essay

Parts of the Brain: Anatomy, Structure & Functions

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

Learn about our Editorial Process

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

On This Page:

The brain controls all functions of the body, interprets information from the outside world, and defines who we are as individuals and how we experience the world.

The brain receives information through our senses: sight, touch, taste, smell, and hearing. This information is processed in the brain, allowing us to give meaning to the input it receives.

The brain is part of the central nervous system ( CNS ) along with the spinal cord. There is also a peripheral nervous system (PNS) comprised of 31 pairs of spinal nerves that branch from the spinal cord and cranial nerves that branch from the brain.

Brain Parts

The brain is composed of the cerebrum, cerebellum, and brainstem (Fig. 1).

Figure 1. The brain has three main parts: the cerebrum, cerebellum, and brainstem.

The cerebrum is the largest and most recognizable part of the brain. It consists of grey matter (the cerebral cortex ) and white matter at the center. The cerebrum is divided into two hemispheres, the left and right, and contains the lobes of the brain (frontal, temporal, parietal, and occipital lobes).

The cerebrum produces higher functioning roles such as thinking, learning, memory, language, emotion, movement, and perception.

The Cerebellum

The cerebellum is located under the cerebrum and monitors and regulates motor behaviors, especially automatic movements.

This structure is also important for regulating posture and balance and has recently been suggested for being involved in learning and attention.

Although the cerebellum only accounts for roughly 10% of the brain’s total weight, this area is thought to contain more neurons (nerve cells) than the rest of the brain combined.

The brainstem is located at the base of the brain. This area connects the cerebrum and the cerebellum to the spinal cord, acting as a relay station for these areas.

The brainstem regulates automatic functions such as sleep cycles, breathing, body temperature, digestion, coughing, and sneezing.

Right Brain vs. Left Brain

The cerebrum is divided into two halves: the right and left hemispheres (Fig. 2). The left hemisphere controls the right half of the body, and the right hemisphere controls the left half.

The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum, consisting of about 200 million axons.

The corpus callosum allows the two hemispheres to communicate and allows information being processed on one side of the brain to be shared with the other.

Figure 2. The cerebrum is divided into left and right hemispheres. The nerve fibers corpus callosum connects the two sides.

Hemispheric lateralization is the idea that each hemisphere is responsible for different functions. Each of these functions is localized to either the right or left side.

The left hemisphere is associated with language functions, such as formulating grammar and vocabulary and containing different language centers (Broca’s and Wernicke’s area).

The right hemisphere is associated with more visuospatial functions such as visualization, depth perception, and spatial navigation. These left and right functions are the case in most people, especially those who are right-handed.

Lobes of the Brain

Each cerebral hemisphere can be subdivided into four lobes, each associated with different functions.

The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes (Figure 3).

Figure 3. The cerebrum is divided into four lobes: frontal, parietal, occipital, and temporal.

Frontal lobes

The frontal lobes are located at the front of the brain, behind the forehead (Figure 4).

Their main functions are associated with higher cognitive functions, including problem-solving, decision-making, attention, intelligence, and voluntary behaviors.

The frontal lobes contain the motor cortex  responsible for planning and coordinating movements.

It also contains the prefrontal cortex, which is responsible for initiating higher-lever cognitive functioning, and Broca’s Area, which is essential for language production.

Figure 4. Frontal lobe structure.

Temporal lobes

The temporal lobes are located on both sides of the brain, near the temples of the head, hence the name temporal lobes (Figure 5).

The main functions of these lobes include understanding, language, memory acquisition, face recognition, object recognition, perception, and auditory information processing.

There is a temporal lobe in both the left and right hemispheres. The left temporal lobe, which is usually the most dominant in people, is associated with language, learning, memorizing, forming words, and remembering verbal information.

The left lobe also contains a vital language center known as Wernicke’s area, which is essential for language development. The right temporal lobe is usually associated with learning and memorizing non-verbal information and determining facial expressions.

Figure 5. Temporal lobe structure.

Parietal lobes

The parietal lobe is located at the top of the brain, between the frontal and occipital lobes, and above the temporal lobes (Figure 6).

The parietal lobe is essential for integrating information from the body’s senses to allow us to build a coherent picture of the world around us.

These lobes allow us to perceive our bodies through somatosensory information (e.g., through touch, pressure, and temperature). It can also help with visuospatial processing, reading, and number representations (mathematics).

The parietal lobes also contain the somatosensory cortex, which receives and processes sensory information, integrating this into a representational map of the body.

This means it can pinpoint the exact area of the body where a sensation is felt, as well as perceive the weight of objects, shape, and texture.

Figure 6. Parietal lobe structure.

Occipital lobes

The occipital lobes are located at the back of the brain behind the temporal and parietal lobes and below the occipital bone of the skull (Figure 7).

The occipital lobes receive sensory information from the eyes’ retinas, which is then encoded into different visual data. Some of the functions of the occipital lobes include being able to assess the size, depth, and distance, determine color information, object and facial recognition, and mapping the visual world.

The occipital lobes also contain the primary visual cortex, which receives sensory information from the retinas, transmitting this information relating to location, spatial data, motion, and the colors of objects in the field of vision.

Figure 7. Occipital lobe structure.

Cerebral Cortex

The surface of the cerebrum is called the cerebral cortex  and has a wrinkled appearance, consisting of bulges, also known as gyri, and deep furrows, known as sulci (Figure 8).

A gyrus (plural: gyri) is the name given to the bumps and ridges on the cerebral cortex (the outermost layer of the brain). A sulcus (plural: sulci) is another name for a groove in the cerebral cortex.

Figure 8. The cortex contains neurons (grey matter) interconnected to other brain areas by axons (white matter). The cortex has a folded appearance. A fold is called a gyrus, and the valley between is a sulcus.

The cerebral cortex is primarily constructed of grey matter (neural tissue made up of neurons), with between 14 and 16 billion neurons found here.

The many folds and wrinkles of the cerebral cortex allow a wider surface area for an increased number of neurons to live there, permitting large amounts of information to be processed.

Deep Structures

The amygdala is a structure deep in the brain that is involved in the processing of emotions and fear learning. The amygdala is a part of the limbic system, a neural network that mediates emotion and memory (Figure 9).

This structure also ties emotional meaning to memories, processes rewards, and helps us make decisions. This structure has also been linked with the fight-or-flight response.

Figure 9. The amygdala in the limbic system plays a key role in how animals assess and respond to environmental threats and challenges by evaluating the emotional importance of sensory information and prompting an appropriate response.

Thalamus and Hypothalamus

The thalamus relays information between the cerebral cortex, brain stem, and other cortical structures (Figure 10).

Because of its interactive role in relaying sensory and motor information, the thalamus contributes to many processes, including attention, perception, timing, and movement. The hypothalamus modulates a range of behavioral and physiological functions.

It controls autonomic functions such as hunger, thirst, body temperature, and sexual activity. To do this, the hypothalamus integrates information from different brain parts and responds to various stimuli such as light, odor, and stress.

Figure 10. The thalamus is often described as the brain’s relay station as a great deal of information that reaches the cerebral cortex first stops in the thalamus before being sent to its destination.

Hippocampus

The hippocampus is a curved-shaped structure in the limbic system associated with learning and memory (Figure 11).

This structure is most strongly associated with the formation of memories, is an early storage system for new long-term memories, and plays a role in the transition of these long-term memories to more permanent memories.

Figure 11. Hippocampus location in the brain

Basal Ganglia

The basal ganglia are a group of structures that regulate the coordination of fine motor movements, balance, and posture alongside the cerebellum.

These structures are connected to other motor areas and link the thalamus with the motor cortex. The basal ganglia are also involved in cognitive and emotional behaviors, as well as playing a role in reward and addiction.

Figure 12. The Basal Ganglia Illustration

Ventricles and Cerebrospinal Fluid

Within the brain, there are fluid-filled interconnected cavities called ventricles , which are extensions of the spinal cord. These are filled with a substance called cerebrospinal fluid, which is a clear and colorless liquid.

The ventricles produce cerebrospinal fluid and transport and remove this fluid. The ventricles do not have a unique function, but they provide cushioning to the brain and are useful for determining the locations of other brain structures.

Cerebrospinal fluid circulates the brain and spinal cord and functions to cushion the brain within the skull. If damage occurs to the skull, the cerebrospinal fluid will act as a shock absorber to help protect the brain from injury.

As well as providing cushioning, the cerebrospinal fluid circulates nutrients and chemicals filtered from the blood and removes waste products from the brain. Cerebrospinal fluid is constantly absorbed and replenished by the ventricles.

If there were a disruption or blockage, this can cause a build-up of cerebrospinal fluid and can cause enlarged ventricles.

Neurons are the nerve cells of the central nervous system that transmit information through electrochemical signals throughout the body. Neurons contain a soma, a cell body from which the axon extends.

Axons are nerve fibers that are the longest part of the neuron, which conduct electrical impulses away from the soma.

There are dendrites at the end of the neuron, which are branch-like structures that send and receive information from other neurons.

A myelin sheath, a fatty insulating layer, forms around the axon, allowing nerve impulses to travel down the axon quickly.

There are different types of neurons. Sensory neurons transmit sensory information, motor neurons transmit motor information, and relay neurons allow sensory and motor neurons to communicate.

The communication between neurons is called synapses. Neurons communicate with each other via synaptic clefts, which are gaps between the endings of neurons.

During synaptic transmission, chemicals, such as neurotransmitters, are released from the endings of the previous neuron (also known as the presynaptic neuron).

These chemicals enter the synaptic cleft to then be transported to receptors on the next neuron (also known as the postsynaptic neuron).

Once transported to the next neuron, the chemical messengers continue traveling down neurons to influence many functions, such as behavior and movement.

Glial Cells

Glial cells are non-neuronal cells in the central nervous system which work to provide the neurons with nourishment, support, and protection.

These are star-shaped cells that function to maintain the environment for neuronal signaling by controlling the levels of neurotransmitters surrounding the synapses.

They also work to clean up what is left behind after synaptic transmission, either recycling any leftover neurotransmitters or cleaning up when a neuron dies.

Oligodendrocytes

These types of glial have the appearance of balls with spikes all around them. They function by wrapping around the axons of neurons to form a protective layer called the myelin sheath.

This is a substance that is rich in fat and provides insulation to the neurons to aid neuronal signaling.

Microglial cells have oval bodies and many branches projecting out of them. The primary function of these cells is to respond to injuries or diseases in the central nervous system.

They respond by clearing away any dead cells or removing any harmful toxins or pathogens that may be present, so they are, therefore, important to the brain’s health.

Ependymal cells

These cells are column-shaped and usually line up together to form a membrane called the ependyma. The ependyma is a thin membrane lining the spinal cord and ventricles of the brain .

In the ventricles, these cells have small hairlike structures called cilia, which help encourage the flow of cerebrospinal fluid.

Cranial Nerves

There are 12 types of cranial nerves which are linked directly to the brain without having to pass through the spinal cord. These allow sensory information to pass from the organs of the face to the brain:

Mnemonic for Order of Cranial Nerves:

S ome S ay M arry M oney B ut M y B rother S ays B ig B rains M atter M ore

• Cranial I: Sensory
• Cranial II: Sensory
• Cranial III: Motor
• Cranial IV: Motor
• Cranial V: Both (sensory & motor)
• Cranial VI: Motor
• Cranial VII: Both (sensory & motor)
• Cranial VIII: Sensory
• Cranial IX: Both (sensory & motor)
• Cranial X: Both (sensory & motor)
• Cranial XI: Motor
• Cranial XII: Motor

Purves, D., Augustine, G., Fitzpatrick, D., Katz, L., LaMantia, A., McNamara, J., & Williams, S. (2001). Neuroscience 2nd edition . sunderland (ma) sinauer associates. Types of Eye Movements and Their Functions.

Mayfield Brain and Spine (n.d.). Anatomy of the Brain. Retrieved July 28, 2021, from: https://mayfieldclinic.com/pe-anatbrain.htm

Robertson, S. (2018, August 23). What is Grey Matter? News Medical Life Sciences. https://www.news-medical.net/health/What-is-Grey-Matter.aspx

Guy-Evans, O. (2021, April 13). Temporal lobe: definition, functions, and location. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/temporal-lobe.html

Guy-Evans, O. (2021, April 15). Parietal lobe: definition, functions, and location. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/parietal-lobe.html

Guy-Evans, O. (2021, April 19). Occipital lobe: definition, functions, and location. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/occipital-lobe.html

Guy-Evans, O. (2021, May 08). Frontal lobe function, location in brain, damage, more. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/frontal-lobe.html

Guy-Evans, O. (2021, June 09). Gyri and sulci of the brain. Simply Psychology. www.www.www.www.www.www.simplypsychology.org/gyri-and-sulci-of-the-brain.html

Masks Strongly Recommended but Not Required in Maryland, Starting Immediately

Due to the downward trend in respiratory viruses in Maryland, masking is no longer required but remains strongly recommended in Johns Hopkins Medicine clinical locations in Maryland. Read more .

• Vaccines  
• Masking Guidelines
• Visitor Guidelines  

Brain Anatomy and How the Brain Works

What is the brain.

The brain is a complex organ that controls thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger and every process that regulates our body. Together, the brain and spinal cord that extends from it make up the central nervous system, or CNS.

What is the brain made of?

Weighing about 3 pounds in the average adult, the brain is about 60% fat. The remaining 40% is a combination of water, protein, carbohydrates and salts. The brain itself is a not a muscle. It contains blood vessels and nerves, including neurons and glial cells.

What is the gray matter and white matter?

Gray and white matter are two different regions of the central nervous system. In the brain, gray matter refers to the darker, outer portion, while white matter describes the lighter, inner section underneath. In the spinal cord, this order is reversed: The white matter is on the outside, and the gray matter sits within.

Gray matter is primarily composed of neuron somas (the round central cell bodies), and white matter is mostly made of axons (the long stems that connects neurons together) wrapped in myelin (a protective coating). The different composition of neuron parts is why the two appear as separate shades on certain scans.

Each region serves a different role. Gray matter is primarily responsible for processing and interpreting information, while white matter transmits that information to other parts of the nervous system.

How does the brain work?

The brain sends and receives chemical and electrical signals throughout the body. Different signals control different processes, and your brain interprets each. Some make you feel tired, for example, while others make you feel pain.

Some messages are kept within the brain, while others are relayed through the spine and across the body’s vast network of nerves to distant extremities. To do this, the central nervous system relies on billions of neurons (nerve cells).

Main Parts of the Brain and Their Functions

At a high level, the brain can be divided into the cerebrum, brainstem and cerebellum.

The cerebrum (front of brain) comprises gray matter (the cerebral cortex) and white matter at its center. The largest part of the brain, the cerebrum initiates and coordinates movement and regulates temperature. Other areas of the cerebrum enable speech, judgment, thinking and reasoning, problem-solving, emotions and learning. Other functions relate to vision, hearing, touch and other senses.

Cerebral Cortex

Cortex is Latin for “bark,” and describes the outer gray matter covering of the cerebrum. The cortex has a large surface area due to its folds, and comprises about half of the brain’s weight.

The cerebral cortex is divided into two halves, or hemispheres. It is covered with ridges (gyri) and folds (sulci). The two halves join at a large, deep sulcus (the interhemispheric fissure, AKA the medial longitudinal fissure) that runs from the front of the head to the back. The right hemisphere controls the left side of the body, and the left half controls the right side of the body. The two halves communicate with one another through a large, C-shaped structure of white matter and nerve pathways called the corpus callosum. The corpus callosum is in the center of the cerebrum.

The brainstem (middle of brain) connects the cerebrum with the spinal cord. The brainstem includes the midbrain, the pons and the medulla.

• Midbrain. The midbrain (or mesencephalon) is a very complex structure with a range of different neuron clusters (nuclei and colliculi), neural pathways and other structures. These features facilitate various functions, from hearing and movement to calculating responses and environmental changes. The midbrain also contains the substantia nigra, an area affected by Parkinson’s disease that is rich in dopamine neurons and part of the basal ganglia, which enables movement and coordination.
• Pons. The pons is the origin for four of the 12 cranial nerves, which enable a range of activities such as tear production, chewing, blinking, focusing vision, balance, hearing and facial expression. Named for the Latin word for “bridge,” the pons is the connection between the midbrain and the medulla.
• Medulla. At the bottom of the brainstem, the medulla is where the brain meets the spinal cord. The medulla is essential to survival. Functions of the medulla regulate many bodily activities, including heart rhythm, breathing, blood flow, and oxygen and carbon dioxide levels. The medulla produces reflexive activities such as sneezing, vomiting, coughing and swallowing.

The spinal cord extends from the bottom of the medulla and through a large opening in the bottom of the skull. Supported by the vertebrae, the spinal cord carries messages to and from the brain and the rest of the body.

The cerebellum (“little brain”) is a fist-sized portion of the brain located at the back of the head, below the temporal and occipital lobes and above the brainstem. Like the cerebral cortex, it has two hemispheres. The outer portion contains neurons, and the inner area communicates with the cerebral cortex. Its function is to coordinate voluntary muscle movements and to maintain posture, balance and equilibrium. New studies are exploring the cerebellum’s roles in thought, emotions and social behavior, as well as its possible involvement in addiction, autism and schizophrenia.

Brain Coverings: Meninges

Three layers of protective covering called meninges surround the brain and the spinal cord.

• The outermost layer, the dura mater , is thick and tough. It includes two layers: The periosteal layer of the dura mater lines the inner dome of the skull (cranium) and the meningeal layer is below that. Spaces between the layers allow for the passage of veins and arteries that supply blood flow to the brain.
• The arachnoid mater is a thin, weblike layer of connective tissue that does not contain nerves or blood vessels. Below the arachnoid mater is the cerebrospinal fluid, or CSF. This fluid cushions the entire central nervous system (brain and spinal cord) and continually circulates around these structures to remove impurities.
• The pia mater is a thin membrane that hugs the surface of the brain and follows its contours. The pia mater is rich with veins and arteries.

Lobes of the Brain and What They Control

Each brain hemisphere (parts of the cerebrum) has four sections, called lobes: frontal, parietal, temporal and occipital. Each lobe controls specific functions.

• Frontal lobe. The largest lobe of the brain, located in the front of the head, the frontal lobe is involved in personality characteristics, decision-making and movement. Recognition of smell usually involves parts of the frontal lobe. The frontal lobe contains Broca’s area, which is associated with speech ability.
• Parietal lobe. The middle part of the brain, the parietal lobe helps a person identify objects and understand spatial relationships (where one’s body is compared with objects around the person). The parietal lobe is also involved in interpreting pain and touch in the body. The parietal lobe houses Wernicke’s area, which helps the brain understand spoken language.
• Occipital lobe. The occipital lobe is the back part of the brain that is involved with vision.
• Temporal lobe. The sides of the brain, temporal lobes are involved in short-term memory, speech, musical rhythm and some degree of smell recognition.

Deeper Structures Within the Brain

Pituitary gland.

Sometimes called the “master gland,” the pituitary gland is a pea-sized structure found deep in the brain behind the bridge of the nose. The pituitary gland governs the function of other glands in the body, regulating the flow of hormones from the thyroid, adrenals, ovaries and testicles. It receives chemical signals from the hypothalamus through its stalk and blood supply.

Hypothalamus

The hypothalamus is located above the pituitary gland and sends it chemical messages that control its function. It regulates body temperature, synchronizes sleep patterns, controls hunger and thirst and also plays a role in some aspects of memory and emotion.

Small, almond-shaped structures, an amygdala is located under each half (hemisphere) of the brain. Included in the limbic system, the amygdalae regulate emotion and memory and are associated with the brain’s reward system, stress, and the “fight or flight” response when someone perceives a threat.

Hippocampus

A curved seahorse-shaped organ on the underside of each temporal lobe, the hippocampus is part of a larger structure called the hippocampal formation. It supports memory, learning, navigation and perception of space. It receives information from the cerebral cortex and may play a role in Alzheimer’s disease.

Pineal Gland

The pineal gland is located deep in the brain and attached by a stalk to the top of the third ventricle. The pineal gland responds to light and dark and secretes melatonin, which regulates circadian rhythms and the sleep-wake cycle.

Ventricles and Cerebrospinal Fluid

Deep in the brain are four open areas with passageways between them. They also open into the central spinal canal and the area beneath arachnoid layer of the meninges.

The ventricles manufacture cerebrospinal fluid , or CSF, a watery fluid that circulates in and around the ventricles and the spinal cord, and between the meninges. CSF surrounds and cushions the spinal cord and brain, washes out waste and impurities, and delivers nutrients.

Blood Supply to the Brain

Two sets of blood vessels supply blood and oxygen to the brain: the vertebral arteries and the carotid arteries.

The external carotid arteries extend up the sides of your neck, and are where you can feel your pulse when you touch the area with your fingertips. The internal carotid arteries branch into the skull and circulate blood to the front part of the brain.

The vertebral arteries follow the spinal column into the skull, where they join together at the brainstem and form the basilar artery , which supplies blood to the rear portions of the brain.

The circle of Willis , a loop of blood vessels near the bottom of the brain that connects major arteries, circulates blood from the front of the brain to the back and helps the arterial systems communicate with one another.

Cranial Nerves

Inside the cranium (the dome of the skull), there are 12 nerves, called cranial nerves:

• Cranial nerve 1: The first is the olfactory nerve, which allows for your sense of smell.
• Cranial nerve 2: The optic nerve governs eyesight.
• Cranial nerve 3: The oculomotor nerve controls pupil response and other motions of the eye, and branches out from the area in the brainstem where the midbrain meets the pons.
• Cranial nerve 4: The trochlear nerve controls muscles in the eye. It emerges from the back of the midbrain part of the brainstem.
• Cranial nerve 5: The trigeminal nerve is the largest and most complex of the cranial nerves, with both sensory and motor function. It originates from the pons and conveys sensation from the scalp, teeth, jaw, sinuses, parts of the mouth and face to the brain, allows the function of chewing muscles, and much more.
• Cranial nerve 6: The abducens nerve innervates some of the muscles in the eye.
• Cranial nerve 7: The facial nerve supports face movement, taste, glandular and other functions.
• Cranial nerve 8: The vestibulocochlear nerve facilitates balance and hearing.
• Cranial nerve 9: The glossopharyngeal nerve allows taste, ear and throat movement, and has many more functions.
• Cranial nerve 10: The vagus nerve allows sensation around the ear and the digestive system and controls motor activity in the heart, throat and digestive system.
• Cranial nerve 11: The accessory nerve innervates specific muscles in the head, neck and shoulder.
• Cranial nerve 12: The hypoglossal nerve supplies motor activity to the tongue.

The first two nerves originate in the cerebrum, and the remaining 10 cranial nerves emerge from the brainstem, which has three parts: the midbrain, the pons and the medulla.

Find a Treatment Center

• Neurology and Neurosurgery

Find Additional Treatment Centers at:

• Howard County Medical Center
• Sibley Memorial Hospital
• Suburban Hospital

Request an Appointment

Facioscapulohumeral Muscular Dystrophy in Children

Moyamoya Disease

Motor Stereotypies

Related Topics

• Science Notes Posts
• Contact Science Notes
• Todd Helmenstine Biography
• Anne Helmenstine Biography
• Free Printable Periodic Tables (PDF and PNG)
• Periodic Table Wallpapers
• Interactive Periodic Table
• Periodic Table Posters
• How to Grow Crystals
• Chemistry Projects
• Fire and Flames Projects
• Holiday Science
• Chemistry Problems With Answers
• Physics Problems
• Unit Conversion Example Problems
• Chemistry Worksheets
• Biology Worksheets
• Periodic Table Worksheets
• Physical Science Worksheets
• Science Lab Worksheets
• My Amazon Books

Parts of the Brain and Their Functions

The human brain is the epicenter of our nervous system and plays a pivotal role in virtually every aspect of our lives. It’s a complex, highly organized organ responsible for thoughts, feelings, actions, and interactions with the world around us. Here is a look at the intricate anatomy of the brain, its functions, and the consequences of damage to different areas.

Introduction to the Brain and Its Functions

The brain is an organ of soft nervous tissue that is protected within the skull of vertebrates. It functions as the coordinating center of sensation and intellectual and nervous activity. The brain consists of billions of neurons (nerve cells) that communicate through intricate networks. The primary functions of the brain include processing sensory information, regulating bodily functions, forming thoughts and emotions, and storing memories.

Main Parts of the Brain – Anatomy

The three main parts of the brain are the cerebrum, cerebellum, and brainstem.

1. Cerebrum

• Location: The cerebellum occupies the upper part of the cranial cavity and is the largest part of the human brain.
• Functions: It’s responsible for higher brain functions, including thought, action, emotion, and interpretation of sensory data.
• Effects of Damage: Depending on the area affected, damage leads to memory loss, impaired cognitive skills, changes in personality, and loss of motor control.

2. Cerebellum

• Location: The cerebellum is at the back of the brain, below the cerebrum.
• Functions: It coordinates voluntary movements such as posture, balance, coordination, and speech.
• Effects of Damage: Damage causes problems with balance, movement, and muscle coordination (ataxia).

3. Brainstem

• Location: The brainstem is lower extension of the brain, connecting to the spinal cord. It includes the midbrain, pons, and medulla oblongata.
• Functions: This part of the brain controls many basic life-sustaining functions, including heart rate, breathing, sleeping, and eating.
• Effects of Damage: Damage results in life-threatening conditions like breathing difficulties, heart problems, and loss of consciousness.

Lobes of the Brain

The four lobes of the brain are regions of the cerebrum:

• Location: This is the anterior or front part of the brain.
• Functions: Decision making, problem solving, control of purposeful behaviors, consciousness, and emotions.
• Location: Sits behind the frontal lobe.
• Functions: Processes sensory information it receives from the outside world, mainly relating to spatial sense and navigation (proprioception).
• Location: Below the lateral fissure, on both cerebral hemispheres.
• Functions: Mainly revolves around auditory perception and is also important for the processing of both speech and vision (reading).
• Location: At the back of the brain.
• Functions: Main center for visual processing.

Left vs. Right Brain Hemispheres

The cerebrum has two halves, called hemispheres. Each half controls functions on the opposite side of the body. So, the left hemisphere controls muscles on the right side of the body, and vice versa. But, the functions of the two hemispheres are not entirely identical:

• Left Hemisphere: It’s dominant in language and speech and plays roles in logical thinking, analysis, and accuracy. .
• Right Hemisphere: This hemisphere is more visual and intuitive and functions in creative and imaginative tasks.

The corpus callosum is a band of nerves that connect the two hemispheres and allow communication between them.

Detailed List of Parts of the Brain

While knowing the three key parts of the brain is a good start, the anatomy is quite a bit more complex. In addition to nervous tissues, the brain also contains key glands:

• Cerebrum: The cerebrum is the largest part of the brain. Divided into lobes, it coordinates thought, movement, memory, senses, speech, and temperature.
• Corpus Callosum : A broad band of nerve fibers joining the two hemispheres of the brain, facilitating interhemispheric communication.
• Cerebellum : Coordinates movement and balance and aids in eye movement.
• Pons : Controls voluntary actions, including swallowing, bladder function, facial expression, posture, and sleep.
• Medulla oblongata : Regulates involuntary actions, including breathing, heart rhythm, as well as oxygen and carbon dioxide levels.
• Limbic System : Includes the amygdala, hippocampus, and parts of the thalamus and hypothalamus.
• Amygdala: Plays a key role in emotional responses, hormonal secretions, and memory formation.
• Hippocampus: Plays a vital role in memory formation and spatial navigation.
• Thalamus : Acts as the brain’s relay station, channeling sensory and motor signals to the cerebral cortex, and regulating consciousness, sleep, and alertness.
• Basal Ganglia : A group of structures involved in processing information related to movement, emotions, and reward. Key structures include the striatum, globus pallidus, substantia nigra, and subthalamic nucleus.
• Ventral Tegmental Area (VTA) : Plays a role in the reward circuit of the brain, releasing dopamine in response to stimuli indicating a reward.
• Optic tectum : Also known as the superior colliculus, it directs eye movements.
• Substantia Nigra : Involved in motor control and contains a large concentration of dopamine-producing neurons.
• Cingulate Gyrus : Plays a role in processing emotions and behavior regulation. It also helps regulate autonomic motor function.
• Olfactory Bulb : Involved in the sense of smell and the integration of olfactory information.
• Mammillary Bodies : Plays a role in recollective memory.
• Function: Regulates emotions, memory, and arousal.

Glands in the Brain

The hypothalamus, pineal gland, and pituitary gland are the three endocrine glands within the brain:

• Hypothalamus : The hypothalamus links the nervous and endocrine systems. It contains many small nuclei. In addition to participating in eating and drinking, sleeping and waking, it regulates the endocrine system via the pituitary gland. It maintains the body’s homeostasis, regulating hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger, and aggressive behavior.
• Pituitary Gland : Known as the “master gland,” it controls various other hormone glands in the body, such as the thyroid and adrenals, as well as regulating growth, metabolism, and reproductive processes.
• Pineal Gland : The pineal gland produces and regulates some hormones, including melatonin, which is crucial in regulating sleep patterns and circadian rhythms.

Gray Matter vs. White Matter

The brain and spinal cord consist of gray matter (substantia grisea) and white matter (substantia alba).

• White Matter: Consists mainly of axons and myelin sheaths that send signals between different brain regions and between the brain and spinal cord.
• Gray Matter: Consists of neuronal cell bodies, dendrites, and axon terminals. Gray matter processes information and directs stimuli for muscle control, sensory perception, decision making, and self-control.

Frequently Asked Questions (FAQs) About the Human Brain

• The human brain contains approximately 86 billion neurons. Additionally, it has a similar or slightly higher number of non-neuronal cells (glial cells), making the total number of cells in the brain close to 170 billion.
• There are about 86 billion neurons in the human brain. These neurons are connected by trillions of synapses, forming a complex networks.
• The average adult human brain weighs about 1.3 to 1.4 kilograms (about 3 pounds). This weight represents about 2% of the total body weight.
• The brain is about 73% water.
• The myth that humans only use 10% of their brain is false. Virtually every part gets use, and most of the brain is active all the time, even during sleep.
• The average size of the adult human brain is about 15 centimeters (6 inches) in length, 14 centimeters (5.5 inches) in width, and 9 centimeters (3.5 inches) in height.
• Brain signal speeds vary depending on the type of neuron and the nature of the signal. They travel anywhere from 1 meter per second to over 100 meters per second in the fastest neurons.
• With age, the brain’s volume and/or weight decrease, synaptic connections reduce, and there can be a decline in cognitive functions. However, the brain to continues adapting and forming new connections throughout life.
• The brain has a limited ability to repair itself. Neuroplasticity aids recovery by allowing other parts of the brain to take over functions of the damaged areas.
• The brain consumes about 20% of the body’s total energy , despite only making up about 2% of the body’s total weight . It requires a constant supply of glucose and oxygen.
• Sleep is crucial for brain health. It aids in memory consolidation, learning, brain detoxification, and the regulation of mood and cognitive functions.
• Douglas Fields, R. (2008). “White Matter Matters”. Scientific American . 298 (3): 54–61. doi: 10.1038/scientificamerican0308-54
• Kandel, Eric R.; Schwartz, James Harris; Jessell, Thomas M. (2000). Principles of Neural Science (4th ed.). New York: McGraw-Hill. ISBN 978-0-8385-7701-1.
• Kolb, B.; Whishaw, I.Q. (2003). Fundamentals of Human Neuropsychology (5th ed.). New York: Worth Publishing. ISBN 978-0-7167-5300-1.
• Rajmohan, V.; Mohandas, E. (2007). “The limbic system”. Indian Journal of Psychiatry . 49 (2): 132–139. doi: 10.4103/0019-5545.33264
• Shepherd, G.M. (1994). Neurobiology . Oxford University Press. ISBN 978-0-19-508843-4.

Related Posts

• Bipolar Disorder
• Therapy Center
• When To See a Therapist
• Types of Therapy
• Best Online Therapy
• Best Couples Therapy
• Best Family Therapy
• Managing Stress
• Sleep and Dreaming
• Understanding Emotions
• Self-Improvement
• Healthy Relationships
• Student Resources
• Personality Types
• Guided Meditations
• Verywell Mind Insights
• 2024 Verywell Mind 25
• Mental Health in the Classroom
• Editorial Process
• Meet Our Review Board
• Crisis Support

Parts of the Brain

Anatomy, Functions, and Conditions

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.

The Cerebral Cortex

The four lobes, the brain stem, the cerebellum, the limbic system, other parts of the brain, brain conditions, protecting your brain.

The human brain  is not only one of the most important organs in the human body; it is also the most complex. The brain is made up of billions of neurons and it also has a number of specialized parts that are each involved in important functions.

While there is still a great deal that researchers do not yet know about the brain, they have learned a great deal about the anatomy and function of the brain. Understanding these parts can help give people a better idea of how disease and damage may affect the brain and its ability to function.

The cerebral cortex is the part of the brain that makes human beings unique. Functions that originate in the cerebral cortex include:

• Consciousness
• Higher-order thinking
• Imagination
• Information processing
• Voluntary physical action

The cerebral cortex is what we see when we look at the brain. It is the outermost portion that can be divided into four lobes. Each bump on the surface of the brain is known as a gyrus, while each groove is known as a sulcus.

The cerebral cortex is the part of the brain that is responsible for a number of complex functions including information processing, language, and memory.

The cerebral cortex can be divided into four sections, which are known as lobes. The frontal lobe, parietal lobe, occipital lobe, and temporal lobe have been associated with different functions ranging from reasoning to auditory perception.

Frontal Lobe

This lobe is located at the front of the brain and is associated with reasoning, motor skills, higher level cognition, and expressive language. At the back of the frontal lobe, near the central sulcus, lies the motor cortex.

The motor cortex receives information from various lobes of the brain and uses this information to carry out body movements. Damage to the frontal lobe can lead to changes in sexual habits, socialization, and attention as well as increased risk-taking .

Parietal Lobe

The parietal lobe is located in the middle section of the brain and is associated with processing tactile sensory information such as pressure, touch, and pain . A portion of the brain known as the somatosensory cortex is located in this lobe and is essential to the processing of the body's senses. 

Temporal Lobe

The temporal lobe is located on the bottom section of the brain. This lobe is also the location of the primary auditory cortex, which is important for interpreting sounds and the language we hear.

The hippocampus is also located in the temporal lobe, which is why this portion of the brain is also heavily associated with the formation of memories . Damage to the temporal lobe can lead to problems with memory, speech perception, and language skills.

Occipital Lobe

The occipital lobe is located at the back portion of the brain and is associated with interpreting visual stimuli and information. The primary visual cortex, which receives and interprets information from the retinas of the eyes, is located in the occipital lobe.

Damage to this lobe can cause visual problems such as difficulty recognizing objects, an inability to identify colors, and trouble recognizing words.

The brain comprises four lobes, each associated with different functions. The frontal lobe is found at the front of the brain; the parietal lobe is behind the frontal lobe; the temporal lobe is located at the sides of the head; and the occipital lobe is found at the back of the head.

The brainstem is an area located at the base of the brain that contains structures vital for involuntary functions such as the heartbeat and breathing. The brain stem is comprised of the midbrain, pons, and medulla.

The midbrain is often considered the smallest region of the brain. It acts as a sort of relay station for auditory and visual information. The midbrain controls many important functions such as the visual and auditory systems as well as eye movement.

Portions of the midbrain called the red nucleus and the substantia nigra are involved in the control of body movement. The darkly pigmented substantia nigra contains a large number of dopamine-producing neurons.

The degeneration of neurons in the substantia nigra is associated with Parkinson’s disease.

The medulla is located directly above the spinal cord in the lower part of the brain stem and controls many vital autonomic functions such as heart rate, breathing, and blood pressure.

The pons connects the cerebral cortex to the medulla and to the cerebellum and serves a number of important functions. It plays a role in several autonomic processes, such as stimulating breathing and controlling sleep cycles.

The brainstem, which includes the midbrain, medulla, and pons, is responsible for involuntary processes, including breathing, heartbeat, and blood pressure.

Sometimes referred to as the ​"little brain," the cerebellum lies on top of the pons behind the brain stem. The cerebellum makes up approximately 10% of the brain's total size , but it accounts for more than 50% of the total number of neurons located in the entire brain .

The cerebellum is comprised of small lobes and serves several functions.

• It receives information from the inner ear's balance system, sensory nerves, and auditory and visual systems. It is involved in the coordination of movements as well as motor learning.
• It is also associated with motor movement and control, but this is not because the motor commands originate here. Instead, the cerebellum modifies these signals and makes motor movements accurate and useful.
• The cerebellum helps control posture, balance, and the coordination of voluntary movements. This allows different muscle groups to act together and produce coordinated fluid movement.
• In addition to playing an essential role in motor control, the cerebellum is also important in certain cognitive functions, including speech.

The cerebrum is the largest part of the brain and is responsible for managing conscious thought, the coordination of movement, learning, speech, behavior, and personality.

Although there is no totally agreed-upon list of the structures that make up the limbic system, four of the main regions include:

The Hypothalamus

The hypothalamus is a grouping of nuclei that lie along the base of the brain near the pituitary gland. The hypothalamus connects with many other regions of the brain and is responsible for controlling hunger, thirst, emotions , body temperature regulation, and circadian rhythms.

The hypothalamus also controls the pituitary gland by secreting hormones. This gives the hypothalamus a great deal of control over many body functions.

The Amygdala

The amygdala is a cluster of nuclei located close to the base of the brain. It is primarily involved in functions including memory, emotion, and the body's fight-or-flight response . The structure processes external stimuli and then relays that information to the hippocampus, which can then prompt a response to deal with outside threats.

The Thalamus

Located above the brainstem, the thalamus processes and transmits movement and sensory information . It is essentially a relay station, taking in sensory information and then passing it on to the cerebral cortex. The cerebral cortex also sends information to the thalamus, which then sends this information to other systems.

The Hippocampus

The hippocampus is a structure located in the temporal lobe. It is important in memory and learning and is sometimes considered to be part of the limbic system because it plays an important part in the control of emotional responses . It plays a role in the body's fight-or-flight response and in the recall and regulation of emotional memories.

The limbic system controls behaviors essential for survival, including the fight or flight response, feeding behavior, and reproduction.

Other important structures play an essential role in supporting the structure and function of the brain. Some of these parts of the brain include:

The meninges are the layers that surround the brain and spinal cord and provide protection. There are three layers of meninges:

• The dura mater : This is the thick, outmost layer located directly under the skull and vertebral column.
• The arachnoid mater : This is a thin layer of web-like connective tissue. Under this layer is cerebrospinal fluid that helps cushion the brain and spinal cord.
• The pia mater : This layer contains veins and arteries and is found directly atop the brain and spinal cord.

The brain also contains 12 cranial nerves. Each nerve plays a vital role in relaying essential information to the brain. These nerves include:

• The olfactory nerve : Essential for the sense of smell
• The optic nerve : Controls eyesight
• The oculomotor nerve : Controls the motions of the eye and the response of the pupil
• The trochlea nerve : Controls the muscles of the ey
• The trigeminal nerve : Carries sensory and motor information to and from the face, jaw, teeth, and scalp
• Abducens nerve : Associated with specific movements of the eye
• Facial nerve : Responsible for sensory and motor functions controlling the face, tongue, tear glands, and parts of the ear
• The vestibulocochlear nerve , which regulates hearing and balance
• The glossopharyngeal nerve : Important for sensory information from parts of the tongue and stimulating specific throat muscles
• The vagus nerve : Plays many important roles, including carrying sensory information from the ear, heart, intestines
• The accessory nerve : Controls the muscles of the neck
• The hypoglossal nerve : Responsible for the muscle movements of the tongue

In addition to the main parts of the brain, there are also other important structures that are important for normal functioning. This includes the protective meninges and the cranial nerves that transmit signals to and from the brain.

The brain can also be affected by a number of conditions and by damage. According to the National Institute of Neurological Disorders and Stroke, there are more than 600 types of neurological diseases. Some conditions that can affect the brain and its function include:

• Brain tumors
• Cerebrovascular diseases such as stroke and vascular dementia
• Convulsive disorders such as epilepsy
• Degenerative diseases such as Alzheimer's disease and Parkinson's disease
• Developmental disorders such as cerebral palsy
• Infectious diseases such as AIDS dementia
• Metabolic diseases such as Gaucher's disease
• Neurogenetic diseases including Huntington's disease and muscular dystrophy
• Trauma such as head injury and spinal cord injury

By studying the brain and learning more about its anatomy and function, researchers are able to develop new treatments and preventative strategies for conditions that affect the brain.

Disease and damage can affect the brain's ability to function. Tumors, strokes, degenerative conditions, trauma, and infectious diseases are just a few of the conditions that can damage the brain.

You can't change your genetics or some other risk factors. But it's important to take steps to help protect the health of your brain.

Diet and Exercise

Research suggests that regular physical activity is essential for brain health. For example, that exercise can help delay brain aging as well as degenerative diseases such as Alzheimer's, diabetes, and multiple sclerosis. It is also associated with improvements in cognitive abilities and memory.

Similarly, a nutritious, balanced diet that includes omega-3 fatty acids, vitamins, and antioxidants is important for brain function (as well as overall health).

It's also essential to protect your brain from injury by, for example, wearing a helmet when participating in physical activities that pose a risk for collision or falls, and always wearing a seatbelt when driving or riding in a car.

Sleep can also play a pivotal role in brain health and mental well-being . Studies have found that sleep can actually play a role in the development and maintenance of some psychiatric conditions including anxiety, depression, and bipolar disorder.

Mental Activity

Evidence also suggests that staying mentally engaged can also play an important role in protecting your brain from some degenerative conditions. Activities that may help include learning new things and staying socially active.

A Word From Verywell

The human brain is remarkably complex and researchers are still discovering many of the mysteries of how the mind works. By better understanding how different parts of the brain function, you can also better appreciate how disease or injury may impact it. If you think that you are experiencing symptoms of a brain condition, talk to your doctor for further evaluation.

Boly M, Massimini M, Tsuchiya N, Postle BR, Koch C, Tononi G. Are the neural correlates of consciousness in the front or in the back of the cerebral cortex? Clinical and neuroimaging evidence . J Neurosci . 2017;37(40):9603-9613. doi:10.1523/JNEUROSCI.3218-16.2017

Jawabri KH, Sharma S. Physiology, cerebral cortex functions . In: StatPearls [Internet]. StatPearls Publishing.

Hurley RA, Flashman LA, Chow TW, Taber KH. The brainstem: anatomy, assessment, and clinical syndromes . J Neuropsychiatry Clin Neurosci . 2010;22(1):iv-7. doi:10.1176/jnp.2010.22.1.iv

Basinger H, Hogg JP. Neuroanatomy, brainstem . In: StatPearls [Internet]. StatPearls Publishing.

Wagner MJ, Kim TH, Savall J, Schnitzer MJ, Luo L. Cerebellar granule cells encode the expectation of reward . Nature . 2017;544(7648):96-100. doi:10.1038/nature21726

Biran J, Tahor M, Wircer E, Levkowitz G. Role of developmental factors in hypothalamic function . Front Neuroanat . 2015;9:47. doi:10.3389/fnana.2015.00047

Baxter MG, Croxson PL. Facing the role of the amygdala in emotional information processing . Proc Nat Acad Sci . 2012;109(52):21180-21181. doi:10.1073/pnas.1219167110

Fama R, Sullivan EV. Thalamic structures and associated cognitive functions: Relations with age and aging . Neurosci Biobehav Rev . 2015;54:29-37. doi:10.1016/j.neubiorev.2015.03.008

Anand KS, Dhikav V. Hippocampus in health and disease: An overview . Ann Indian Acad Neurol . 2012;15(4):239-46. doi:10.4103/0972-2327.104323

Zhu Y, Gao H, Tong L, et al. Emotion regulation of hippocampus using real-time fmri neurofeedback in healthy human . Front Hum Neurosci . 2019;13:242. doi:10.3389/fnhum.2019.00242 

National Institute of Neurological Disorders and Stroke. Brain basics: know your brain .

Di Liegro CM, Schiera G, Proia P, Di Liegro I. Physical activity and brain health .  Genes (Basel) . 2019;10(9):720. doi:10.3390/genes10090720

Scott AJ, Webb TL, Rowse G.  Does improving sleep lead to better mental health?. A protocol for a meta-analytic review of randomised controlled trials .  BMJ Open . 2017;7(9):e016873. doi:10.1136/bmjopen-2017-016873

Sommerlad A, Sabia S, Singh-manoux A, Lewis G, Livingston G.  Association of social contact with dementia and cognition: 28-year follow-up of the Whitehall II cohort study .  PLoS Med . 2019;16(8):e1002862. doi:10.1371/journal.pmed.1002862

Carter R. The Human Brain Book . Penguin; 2014.

Kalat JW. Biological Psychology . Cengage Learning; 2016. 

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Anatomy of the Brain

• Cell Biology
• Weather & Climate

Brain Divisions

Anatomy of the brain: structures, brain ventricles, more about the brain.

• B.A., Biology, Emory University
• A.S., Nursing, Chattahoochee Technical College

The anatomy of the brain is complex due its intricate structure and function. This amazing organ acts as a control center by receiving, interpreting, and directing sensory information throughout the body. The brain and spinal cord are the two main structures of the central nervous system . There are three major divisions of the brain. They are the forebrain, the midbrain, and the hindbrain.

Key Takeaways

• The forebrain, the midbrain, and the hindbrain are the three main parts of the brain.
• The forebrain has two major parts called the diencephalon and the telencephalon. The forebrain is responsible for a number of functions related to thinking, perceiving, and evaluating sensory information.
• The midbrain, also called the mesencephalon, connects the hindbrain and the forebrain. It is associated with motor functions and auditory and visual responses.
• The hindbrain contains both the metencephalon and the myelencephalon. The hindbrain is associated with balance and equilibrium and the coordination of movement along with autonomic functions like our breathing and our heart rate.
• Both the midbrain and the hindbrain make up the brainstem.

The forebrain is the division of the brain that is responsible for a variety of functions including receiving and processing sensory information, thinking, perceiving, producing and understanding language, and controlling motor function. There are two major divisions of forebrain: the diencephalon and the telencephalon. The diencephalon contains structures such as the thalamus and hypothalamus which are responsible for such functions as motor control, relaying sensory information, and controlling autonomic functions. The telencephalon contains the largest part of the brain, the cerebrum . Most of the actual information processing in the brain takes place in the cerebral cortex .

The midbrain and the hindbrain together make up the brainstem . The midbrain or mesencephalon , is the portion of the brainstem that connects the hindbrain and the forebrain. This region of the brain is involved in auditory and visual responses as well as motor function.

The hindbrain extends from the spinal cord and is composed of the metencephalon and myelencephalon. The metencephalon contains structures such as the pons and cerebellum . These regions assists in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information. The myelencephalon is composed of the medulla oblongata which is responsible for controlling such autonomic functions as breathing, heart rate, and digestion.

The brain contains various structures that have a multitude of functions. Below is a list of major structures of the brain and some of their functions. Basal Ganglia

• Involved in cognition and voluntary movement
• Diseases related to damages of this area are Parkinson's and Huntington's
• Relays information between the peripheral nerves and spinal cord to the upper parts of the brain
• Consists of the midbrain, medulla oblongata, and the pons

Broca's Area

• Speech production
• Understanding language

Central Sulcus (Fissure of Rolando)

• Deep grove that separates the parietal and frontal lobes
• Controls movement coordination
• Maintains balance and equilibrium

Cerebral Cortex

• Outer portion (1.5mm to 5mm) of the cerebrum
• Receives and processes sensory information
• Divided into cerebral cortex lobes

Cerebral Cortex Lobes

• Frontal Lobes -involved with decision-making, problem solving, and planning
• Occipital Lobes -involved with vision and color recognition
• Parietal Lobes - receives and processes sensory information
• Temporal Lobes - involved with emotional responses, memory, and speech
• Largest portion of the brain
• Consists of folded bulges called gyri that create deep furrows

Corpus Callosum

• Thick band of fibers that connects the left and right brain hemispheres

Cranial Nerves

• Twelve pairs of nerves that originate in the brain, exit the skull, and lead to the head, neck and torso

Fissure of Sylvius (Lateral Sulcus)

• Deep grove that separates the parietal and temporal lobes

Limbic System Structures

• Amygdala - involved in emotional responses, hormonal secretions, and memory
• Cingulate Gyrus - a fold in the brain involved with sensory input concerning emotions and the regulation of aggressive behavior
• Fornix - an arching, fibrous band of white matter axons (nerve fibers) that connect the hippocampus to the hypothalamus
• Hippocampus - sends memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrieves them when necessary
• Hypothalamus - directs a multitude of important functions such as body temperature, hunger, and homeostasis
• Olfactory Cortex - receives sensory information from the olfactory bulb and is involved in the identification of odors
• Thalamus - mass of gray matter cells that relay sensory signals to and from the spinal cord and the cerebrum

Medulla Oblongata

• Lower part of the brainstem that helps to control autonomic functions
• Membranes that cover and protect the brain and spinal cord

Olfactory Bulb

• Bulb-shaped end of the olfactory lobe
• Involved in the sense of smell

Pineal Gland

• Endocrine gland involved in biological rhythms
• Secretes the hormone melatonin

Pituitary Gland

• Endocrine gland involved in homeostasis
• Regulates other endocrine glands
• Relays sensory information between the cerebrum and cerebellum

Wernicke's Area

• Region of the brain where spoken language is understood

Cerebral Peduncle

• anterior portion of the midbrain consisting of large bundles of nerve fiber tracts that connect the forebrain to the hindbrain

Reticular Formation

• Nerve fibers located inside the brainstem and a component of the tegmentum ( midbrain )
• Regulates awareness and sleep

Substantia Nigra

• Helps to control voluntary movement and regulates mood ( midbrain )
• The dorsal region of the mesencephalon ( midbrain )
• Assists in visual and auditory reflexes
• The ventral region of the mesencephalon ( midbrain )
• Includes the reticular formation and the red nucleus

Ventricular System - connecting system of internal brain cavities filled with cerebrospinal fluid

• Aqueduct of Sylvius - canal that is located between the third ventricle and the fourth ventricle
• Choroid Plexus - produces cerebrospinal fluid
• Fourth Ventricle - canal that runs between the pons, medulla oblongata, and the cerebellum
• Lateral Ventricle - largest of the ventricles and located in both brain hemispheres
• Third Ventricle - provides a pathway for cerebrospinal fluid to flow

For additional information about the brain, see Divisions of the Brain . Would you like to test your knowledge of the human brain? Take the Human Brain Quiz!

• Divisions of the Brain: Forebrain, Midbrain, Hindbrain
• Brainstem: Function and Location
• Functions of the Central Nervous System
• Anatomy of the Cerebellum and its Function
• Where in the Brain Is the Pons
• Anatomy of the Brain: Your Cerebrum
• Overview of the Medulla Oblongata
• Learn About the Mesencephalon (Midbrain) Function and Structures
• Basic Parts of the Brain and Their Responsibilities
• Get a Description and Diagram of Thalamus Gray Matter
• Third Ventricle
• Hypothalamus Activity and Hormone Production
• Diencephalon Section of the Brain
• The Limbic System of the Brain
• White Matter and Your Brain
• Amygdala's Location and Function

Advertisement

Introduction: The Human Brain

By Helen Phillips

4 September 2006

A false-colour Magnetic Resonance Image (MRI) of a mid-sagittal section through the head of a normal 42 year-old woman, showing structures of the brain, spine and facial tissues

(Image: Mehau Kulyk / Science Photo Library)

The brain is the most complex organ in the human body. It produces our every thought, action , memory , feeling and experience of the world. This jelly-like mass of tissue, weighing in at around 1.4 kilograms, contains a staggering one hundred billion nerve cells, or neurons .

The complexity of the connectivity between these cells is mind-boggling. Each neuron can make contact with thousands or even tens of thousands of others, via tiny structures called synapses . Our brains form a million new connections for every second of our lives. The pattern and strength of the connections is constantly changing and no two brains are alike.

It is in these changing connections that memories are stored, habits learned and personalities shaped , by reinforcing certain patterns of brain activity, and losing others.

Grey matter

While people often speak of their “ grey matter “, the brain also contains white matter . The grey matter is the cell bodies of the neurons, while the white matter is the branching network of thread-like tendrils – called dendrites and axons – that spread out from the cell bodies to connect to other neurons.

But the brain also has another, even more numerous type of cell, called glial cells . These outnumber neurons ten times over. Once thought to be support cells, they are now known to amplify neural signals and to be as important as neurons in mental calculations. There are many different types of neuron, only one of which is unique to humans and the other great apes, the so called spindle cells .

Brain structure is shaped partly by genes , but largely by experience . Only relatively recently it was discovered that new brain cells are being born throughout our lives – a process called neurogenesis . The brain has bursts of growth and then periods of consolidation , when excess connections are pruned. The most notable bursts are in the first two or three years of life, during puberty , and also a final burst in young adulthood.

How a brain ages also depends on genes and lifestyle too. Exercising the brain and giving it the right diet can be just as important as it is for the rest of the body.

Chemical messengers

The neurons in our brains communicate in a variety of ways. Signals pass between them by the release and capture of neurotransmitter and neuromodulator chemicals, such as glutamate , dopamine , acetylcholine , noradrenalin , serotonin and endorphins .

Some neurochemicals work in the synapse , passing specific messages from release sites to collection sites, called receptors. Others also spread their influence more widely, like a radio signal , making whole brain regions more or less sensitive.

These neurochemicals are so important that deficiencies in them are linked to certain diseases. For example, a loss of dopamine in the basal ganglia, which control movements, leads to Parkinson’s disease . It can also increase susceptibility to addiction because it mediates our sensations of reward and pleasure.

Similarly, a deficiency in serotonin , used by regions involved in emotion, can be linked to depression or mood disorders, and the loss of acetylcholine in the cerebral cortex is characteristic of Alzheimer’s disease .

Brain scanning

Within individual neurons, signals are formed by electrochemical pulses. Collectively, this electrical activity can be detected outside the scalp by an electroencephalogram (EEG).

These signals have wave-like patterns , which scientists classify from alpha (common while we are relaxing or sleeping ), through to gamma (active thought). When this activity goes awry, it is called a seizure . Some researchers think that synchronising the activity in different brain regions is important in perception .

Other ways of imaging brain activity are indirect. Functional magnetic resonance imaging ( fMRI ) or positron emission tomography ( PET ) monitor blood flow. MRI scans, computed tomography ( CT ) scans and diffusion tensor images (DTI) use the magnetic signatures of different tissues, X-ray absorption, or the movement of water molecules in those tissues, to image the brain.

These scanning techniques have revealed which parts of the brain are associated with which functions . Examples include activity related to sensations , movement, libido , choices , regrets , motivations and even racism . However, some experts argue that we put too much trust in these results and that they raise privacy issues .

Before scanning techniques were common, researchers relied on patients with brain damage caused by strokes , head injuries or illnesses, to determine which brain areas are required for certain functions . This approach exposed the regions connected to emotions , dreams , memory , language and perception and to even more enigmatic events, such as religious or “ paranormal ” experiences.

One famous example was the case of Phineas Gage , a 19 th century railroad worker who lost part of the front of his brain when a 1-metre-long iron pole was blasted through his head during an explosion. He recovered physically, but was left with permanent changes to his personality , showing for the first time that specific brain regions are linked to different processes.

Structure in mind

The most obvious anatomical feature of our brains is the undulating surfac of the cerebrum – the deep clefts are known as sulci and its folds are gyri. The cerebrum is the largest part of our brain and is largely made up of the two cerebral hemispheres . It is the most evolutionarily recent brain structure, dealing with more complex cognitive brain activities.

It is often said that the right hemisphere is more creative and emotional and the left deals with logic, but the reality is more complex . Nonetheless, the sides do have some specialisations , with the left dealing with speech and language , the right with spatial and body awareness.

See our Interactive Graphic for more on brain structure

Further anatomical divisions of the cerebral hemispheres are the occipital lobe at the back, devoted to vision , and the parietal lobe above that, dealing with movement , position, orientation and calculation .

Behind the ears and temples lie the temporal lobes , dealing with sound and speech comprehension and some aspects of memory . And to the fore are the frontal and prefrontal lobes , often considered the most highly developed and most “human” of regions, dealing with the most complex thought, decision making , planning, conceptualising, attention control and working memory. They also deal with complex social emotions such as regret , morality and empathy .

Another way to classify the regions is as sensory cortex and motor cortex , controlling incoming information, and outgoing behaviour respectively.

Below the cerebral hemispheres, but still referred to as part of the forebrain, is the cingulate cortex , which deals with directing behaviour and pain . And beneath this lies the corpus callosum , which connects the two sides of the brain. Other important areas of the forebrain are the basal ganglia , responsible for movement , motivation and reward.

Urges and appetites

Beneath the forebrain lie more primitive brain regions. The limbic system , common to all mammals, deals with urges and appetites. Emotions are most closely linked with structures called the amygdala , caudate nucleus and putamen . Also in the limbic brain are the hippocampus – vital for forming new memories; the thalamus – a kind of sensory relay station; and the hypothalamus , which regulates bodily functions via hormone release from the pituitary gland .

The back of the brain has a highly convoluted and folded swelling called the cerebellum , which stores patterns of movement, habits and repeated tasks – things we can do without thinking about them.

The most primitive parts, the midbrain and brain stem , control the bodily functions we have no conscious control of, such as breathing , heart rate, blood pressure, sleep patterns , and so on. They also control signals that pass between the brain and the rest of the body, through the spinal cord.

Though we have discovered an enormous amount about the brain, huge and crucial mysteries remain. One of the most important is how does the brain produces our conscious experiences ?

The vast majority of the brain’s activity is subconscious . But our conscious thoughts, sensations and perceptions – what define us as humans – cannot yet be explained in terms of brain activity.

• psychology /

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox! We'll also keep you up to date with New Scientist events and special offers.

More from New Scientist

Explore the latest news, articles and features

Rat neuron injection lets mice that can’t smell sniff out cookies

Songs that birds 'sing' in their dreams translated into sound.

Subscriber-only

Chatbots can persuade conspiracy theorists their view might be wrong

How science can inspire 'peak experiences' that improve well-being, popular articles.

Trending New Scientist articles

Choose Your Test

Sat / act prep online guides and tips, the 3 major parts of the brain and what they do.

General Education

Mission control. Command center. Control tower. No, I'm not talking about space or your laptop hard drive, or even airport flight control. I'm talking about the human brain—the most complex and essential organ our bodies have. What is the brain structure? What part of the brain controls emotions?

Whether you're studying it in class, preparing for an AP exam, or just curious about brain structure, in this article, you'll learn about the main parts of brain anatomy and their functions and as well as get a general overview of the brain's supporting cast.

What Is the Brain and Why Does It Matter?

The brain is a three-pound organ that serves as headquarters for our bodies. Without it, we wouldn't be able to process information, move our limbs, or even breathe . Together with the spinal cord, brain structure and function helps control the central nervous system—the main part of two that make up the human nervous system. (The other part, the peripheral nervous system, is made up of nerves and neurons that connect the central nervous system to the body's limbs and organs.) The human nervous system is responsible for helping us think, breathe, move, react and feel.

Like any good command center, there is a structure to the brain and its operations that help it carry out its basic functions.

What Are the Main Parts of the Brain?

There are three main parts of the brain: the cerebrum, cerebellum and the brain stem.

Image source: Denise Wawrzyniak , used under CC BY-NC 4.0

What Is the Cerebrum?

Was I A Bee /Wikimedia Commons

The cerebrum is the largest part of the brain. Located in the front and middle part of the brain, it accounts for 85% of the brain's weight. Of the three main parts of the brain, the cerebrum is considered the most recent to develop in human evolution. The cerebrum is responsible for all voluntary actions (e.g.: motor skills), communication, emotions, creativity, intelligence and personality.

What Are the Main Parts of the Cerebrum?

The cerebrum's structure is made up of:

What Are the Layers of the Cerebrum?

The cerebrum has two layers: one inner and one outer . The outer layer is known as the cerebral cortex (represented in red in the spinning image above). Most times, whenever you see photos of the brain, you are looking at the cerebral cortex. This area houses the brain's "gray matter," and is considered the "seat" of human consciousness. Higher brain functions such as thinking, reasoning, planning, emotion, memory, the processing of sensory information and speech all happen in the cerebral cortex. In other words, the cerebral cortex is what sets humans apart from other species.

The cerebral cortex is referred to as "gray matter," due to its color and is responsible for several vital functions, such as those listed above.

What Is the Corpus Callosum?

The cerebrum's inner core houses the brain's "white matter." The major part of the inner core is known as the corpus callosum. The corpus callosum is a thick tract of fibrous nerves that serve as a kind of switchboard enabling the brain's hemispheres to communicate with one another. Whereas the cerebral cortex is the cerebrum's outer layer made up of gray matter, and is responsible for thinking, motor function and information processing; the corpus callosum is the cerebrum's inner core, made up of white matter, with four parts of nerve tracts connecting to different parts of the hemispheres.

Home of the white matter: corpus callosum./ Life Sciences Database /Wikimedia Commons

The corpus callosum's nerve fibers (or axons) are coated with myelin. This fatty substance helps increase the transmission of information between the next part of the cerebrum: the two hemispheres.

The Cerebrum's Left and Right Hemispheres

In addition to two layers, the cerebrum also has two halves, or hemispheres: the left hemisphere and the right hemisphere. Although each hemisphere is known for managing different functions, it is important to note that both handle most processes of the brain structure.

The existence of the hemispheres is vital to our body's functions. The relationship between our brain and body is contralateral. This means, generally speaking, that the left side of the brain (left hemisphere) controls the right side of the body, and the right side of the brain (right hemisphere) controls the left side of the body. Because the hemispheres carry out different tasks, they need to "talk" to one another in real time to coordinate our movements, thoughts, etc.

The left hemisphere is responsible for controlling the right side of the body. It handles language, reasoning, logic and speech. If the left hemisphere were a set of classes in school, it would be your math, science, and English classes.

The right hemisphere is responsible for controlling the left side of the body. It handles spatially-related tasks and visual understanding. In terms of classes, the right hemisphere would be your arts, music, and creative writing classes.

The deep groove separating the hemispheres is called the longitudinal fissure (or, cerebral fissure).

The longitudinal fissure is prevented from completely splitting the cerebrum in half by the corpus callosum. Thanks to the corpus callosum (our brain's speedy switchboard), the left side of your brain can chat instantaneously with the right side of your brain.

The red line down the center of the cerebrum is the longitudinal fissure. Life Sciences Database /Wikimedia Commons

All this hemisphere talk brings us to the final part of the cerebrum: the four lobes.

What Are the 4 Lobes of the Brain?

Database Center for Life Sciences /Wikimedia Commons

The cerebrum's left and right hemispheres are each divided into four lobes: the frontal, parietal, occipital and temporal lobes. The lobes generally handle different functions, but much like the hemispheres, the lobes don't function alone. The lobes are separated from each other by depressions in the cortex known as sulcus (or sulci) and are protected by the skull with bones named after their corresponding lobes.

Cancer Research UK /Wikimedia Commons

The frontal lobe is located in the front of the brain, running from your forehead to your ears. It is responsible for problem-solving and planning, thought, behavior, speech, memory and movement. The frontal lobe is separated from the parietal lobe by the central sulcus and is protected by a singular frontal skull bone.

The parietal lobe picks up where the frontal lobe ends and goes until the mid-back part of the brain (about where a ponytail would be). It is responsible for processing information from the senses (touch, sight, hearing, smelling and sight), as well as language interpretation and spatial perception. It is separated from the other lobes on all four sides: from the frontal lobe by central sulcus; from the opposite hemisphere by the longitudinal fissure; from the occipital lobe by parieto-occipital sulcus; and from the temporal lobe below by a depression known as the lateral sulcus, or lateral fissure. Because each hemisphere has a parietal lobe, there are two parietal skull bones—one on the external side of each hemisphere.

The occipital lobe is located in the back of the brain. It is considered the brain's "visual processing center" because it's where the bulk of information our eyes take in gets analyzed and sorted. It is separated from the parietal lobe by the parieto-occipital sulcus; from the temporal lobe by the lateral occipital sulcus; and from the cerebellum (the second part of the brain, coming up soon) by what is called the cerebellar tentorium (or tentorium cerebelli). It is protected by the skull's singular occipital bone.

The temporal lobe is located in behind and below the frontal lobe (and beneath the parietal lobe), under the lateral fissure. It is responsible for our memory, emotions, language and speech, and auditory and visual processing. It is separated from the parietal and frontal lobe by the lateral sulcus (lateral fissure); from the occipital lobe by the lateral occipital sulcus and occipitotemporal sulcus; and is adjacent to the corpus callosum. Similar to its parietal neighbor, the temporal lobe is protected by two bones—one temporal bone on the external side of each hemisphere.

The brain's lobes serve as a map for understanding where brain functions happen. Image source: Denise Wawrzyniak , used under CC BY-NC 4.0

What Is the Cerebellum?

The cerebellum stands for "little brain" in Latin. It looks like a separate mini-brain behind and underneath the cerebrum (beneath the temporal and occipital lobes) and above the brain stem. The cerebellum (along with the brain stem) is considered evolutionarily to be the oldest part of the brain.

Where the cerebrum makes up 85% of the brain's mass, the cerebellum takes up only 10%. However, the cerebellum accounts for more than half of the brain's neurons. The cerebellum is responsible for voluntary movements, coordination, balance, posture, muscle tone, and cognitive functions.

What Are the Main Parts of the Cerebellum?

The cerebellum's structure is made up of:

The Cerebellum's Inner and Outer Layers

Like the cerebrum, the cerebellum has two layers: one inner and one outer. The outer layer is called the cerebellar cortex. Like the cerebral cortex, it is full of gray matter. Functions such as movement, motor learning, balance and posture happen here.

Underneath the cortex lies the cerebellum's white matter. Called "arbor vitae" ("tree of life") for its appearance, the cerebellum's white matter contains cerebellar nuclei. These neurons are vital because they relay information between the cerebral cortex and the peripheral nervous system to assist in learning and cognitive functions, motor control, balance and coordination. (In a very loose parallel, both the cerebellar nuclei of the cerebellum and the corpus callosum of the cerebrum are responsible for internal communications: The corpus callosum relays messages between there cerebrum's hemispheres, and the cerebellar nuclei relays messages between the body and cerebrum.)

The Cerebellum's Left and Right Hemispheres

The cerebellum also has two hemispheres: the left cerebellar hemisphere and the right cerebellar hemisphere. Just as the longitudinal fissure divides the cerebrum's hemispheres, the "vermis" (Latin for "worm") separates the cerebellum's hemispheres.

The Database Center for Life Science /Wikimedia Commons

Cerebellar hemispheres seen from front (r) and back (l)/ The Database Center for Life Science/ Wikimedia Commons

What Are the Three Lobes of the Cerebellum?

The cerebellum's hemispheres are each divided into three lobes: the anterior lobe, posterior lobe, and the flocculonodular lobe. These lobes are split up by two fissures (grooves), called the primary fissure and the posterolateral fissure.

The three lobes of the Cerebellum, where purple is the anterior lobe, green is the posterior lobe and orange is the Flocculonodular lobe. /Database Center for Life Science /Wikimedia Commons

Unlike the cerebral cortex, there are no clear separation of functions in the cerebellar cortex. The best way to identify the tasks are by the information each section processes.

Spinocerebellum

The anterior lobe and the vermis together are known as the spinocerebellum. The spinocerebellum helps regulate muscle tone and body movement. It's also responsible for our sense of our body's position in relation to our surroundings, and in relation to other parts of our body (a.k.a.: proprioceptive information). This area receives input from our spinal cord, auditory and visual systems.

Cerebrocerebellum

The posterior lobe (the cerebellar hemispheres at large, not including the vermis and anterior lobe) is called the cerebrocerebellum. This area is responsible for planning movements that are about to happen, managing sensory information to determine action and motor learning. It receives information from the cerebral cortex (the parietal lobe).

Vestibulocerebellum

The flocculonodular lobe is referred to as the vestibulocerebellum. This area is responsible for managing our eye movement and balance. Unlike the other two areas, this one gets data directly from a sensory nerve, the vestibular nerve. (The vestibular nerve is connected to the vestibular system, which is responsible for our sense of balance and spatial orientation.) This area receives information from the visual cortex.

What Are the Four Nuclei of the Cerebellum?

As the three lobes take in information from the cerebrum, spinal cord and body, the cerebellum also has a way of sending out information. This is done through what are called nuclei—a bundle or neurons embedded deep in the cerebellum's white matter.

Rounding out cerebellum's composition are the four nuclei that pass information between the cerebrum and the body. These nuclei are: dentate, emboliform, globose, and fastcgi. They receive on the body and give information from the cerebellum through Purkinje cells (neurons) and mossy fibers.

What Is the Brain Stem?

Life Sciences Database /Wikimedia Commons

The final section of the brain is a mass of tissue and nerves called the brain stem. Located underneath the cerebrum and cerebellum, the brain stem connects the brain to the spinal cord. All information that goes from the brain to the body (or vice versa), must pass through the brain stem to reach its destination. The brain stem accounts for the remaining 5% of the brain's mass, and is (along with the cerebellum), the oldest part of the brain. The brain stem is responsible for regulating the heart and lungs, communications between the brain and the peripheral nervous system (the nerves of the body), our sleep cyc le, and coordinating reflexes.

The brain stem plugs the brain (central nervous system) into the rest of the body through the spinal cord (peripheral nervous system).

Running throughout the brain stem is an area known as the "reticular formation." This collection of nuclei plays a vital role in managing our consciousness (e.x.: sleep and alertness) and connecting with the various motor nerves to help us move our heads and faces, regulate our involuntary actions, and to help us chew, eat, breathe and see.

What Are the Main Parts of the Brain Stem?

The brain stem is made up of three parts: the midbrain, the pons and the medulla.

BruceBlaus /Wikimedia Commons

Life Sciences Database/ Wikimedia Commons

The midbrain is located underneath the cerebral cortex, near the top of the brain stem. It connects the cerebrum to the brain stem. The midbrain helps process visual and auditory information, such as controlling the eyes and eyelids. It also plays a role in regulating our body temperature and motor movements.

Main Parts of the Midbrain

Pons is the Latin word for "bridge." The pons is responsible for connecting the brain stem to the cerebral cortex and the cerebrum to the cerebellum. It can be found right underneath the midbrain and above the medulla oblongata. Although it is the largest section of the brain stem, the pons is only about 2.5 centimeters long. The pons is responsible for assisting in motor functions, particularly for nerves in the face, ears, and eyes. It also plays a role in regulating the intensity and frequency of breathing. It has both gray and white matter, but it does share gray matter with the midbrain. The reticular formation of the pons' gray matter plays a vital role in dreaming and REM (deep) sleep.

Medulla Oblongata

The medulla oblongata is located behind and partially underneath the cerebellum. It is responsible for our life-sustaining involuntary (autonomic) actions such as breathing, regulating the heartbeat and blood pressure, and reflexes such as sneezing, vomiting and coughing.

Like the pons, the medulla also has gray and white matter. Some of its white matter is shared with the spinal cord, while its gray matter processes cranial nerve information. The reticular formation in the medulla's gray matter assists with breathing and controlling the heart rate.

The Cerebellar Peduncles

Earlier, we learned how four nuclei are responsible for connecting the cerebellum to the body. To connect the cerebellum to the brain stem, the brain depends on nerve tracts called cerebellar peduncles. The cerebellar peduncles help process and analyze motor and sensory information, such as the position of our joints and limbs. There are six cerebellar peduncles (three for each hemisphere) with both white and gray matter. The six cerebellar peduncles are: superior (2), middle (2) and inferior (2).

What Are the Regions of the Brain and How Do They Fit Into the Brain Structure?

The three main parts of the brain are split amongst three regions developed during the embryonic period: the forebrain, midbrain and hindbrain. Together, these regions act as a useful map to understanding the various parts of the brain's structure and functions.

The forebrain, midbrain and hindbrain serve as regions that make finding the various parts of the brain easier./ BruceBlaus /Wikimedia Commons

To better understand the roles of the forebrain, midbrain and hindbrain within the brain, check out the short video below:

The Brain's Support System

While we've covered the basics of brain anatomy, there are a few other supporting players that assist the brain in its role as our command center.

Protective cushioning

Arielinson /Wikimedia Commons

The brain is surrounded by the cranium, or skull. The skull's job is to house the brain and protect its soft tissue from trauma and the elements. The skull is made up of 22 bones, along with fibrous joints called sutures, that keep the brain safe from external injury.

Cushioning the brain from the skull are the meninges. The meninges are three layers of tissue known as the dura mater, arachnoid & pia mater. These layers protect the brain from being displaced; separate the cerebrum from the cerebellum; transfer food and waste from the brain to the body; and clean the brain's fluid to keep it running.

Food and Waste Transport

The cerebrospinal fluid is responsible for bringing in nutrients and removing waste in the brain and spinal cord. It is found in the meninges layers and is moved through the brain by ventricles.

The brain's four main ventricles (spaces) help the cerebrospinal fluid nourish and cleanse the brain. They also cushion the brain from injury.

Information Transport and Boundary Assistants

The gyrus (plural: gyri) and sulcus (sulci) are what give the brain its wrinkly appearance. The grooves (or fissures) of the brain are known as the sulci, while the bumps (or ridges) are called the gyri. These folds and ridges help increase how much of the cerebral cortex can fit into the skull. They also create boundaries between the different sections of the brain, such as the two hemispheres and four lobes of the cerebrum.

Albert Kok /Wikimedia Commons

The gyri and sulci create the wrinkles we traditionally associate with the brain./ Bruce Blaus /Wikimedia Commons

The heart pumps blood to the brain through two arteries: the carotid and vertebral. Because of the brain's importance to the body and the fact that brain cells die without constant blood flow, the heart sends about 20% of the body's bloody supply to the brain. The blood brings oxygen and other nutrients the brain needs to regulate itself and function properly.

The heart pumps blood in and out of the body through the carotid and vertebral arteries.

Neurons and Glial Cells

The human brain has about 80-100 billion neurons, and roughly the same of glial cells. Neurons and glial cells help coordinate and transport signals within the human nervous system. While neurons communicate and receive information with cells, glial cells protect and support neurons in completing their mission.

Cranial Nerves

Twelve cranial nerves help transport information from the brain and body. These motor and sensory nerves are part of the peripheral nervous system and are responsible for controlling muscles and processing information from the organs and bringing it to the brain. These include our senses of sight and smell, as well as our balance and hearing.

The twelve nerves are named for their function and include: the olfactory nerve, optic nerve, oculomotor nerve, trochlear nerve, trigeminal nerve, abducens nerve, facial nerve, vestibulocochlear nerve, glossopharyngeal nerve, vagus nerve, spinal accessory nerve, and hypoglossal nerve.

In Conclusion: Brain Anatomy

The human brain is an incredibly complex, hardworking organ. As one-half of the human nervous system, the brain structure oversees nearly all of the body's operations, including how we move, think, feel and understand ourselves and the world around us. And knowing all this brain anatomy is important. From the cerebrum, cerebellum and the brain stem, to all the parts in between: this three-pound organ is what makes us humans, well, human.

What's Next?

Want to gain medical experience before starting college ? Check out 59 medical programs available for high school students .

Prepping for an AP Biology exam and need some help? Find out what books you need with our Best AP Biology Books of 2019 .

Interested in medical school? Learn what it takes to become a medical student with our guide to pre-med and the main requirements for medical school .

Brittany Logan graduated from Columbia University Graduate School of Journalism with a Master of Science with Honors. She has a dual-degree Master's from Sciences Po School of Journalism in Paris, and earned her Bachelor’s in Global Studies from the University of California, Santa Barbara. She has spent several years working in higher education- including as an English teacher abroad and as a teaching assistant in science writing at Columbia University’s Earth Institute.

Ask a Question Below

Have any questions about this article or other topics? Ask below and we'll reply!

Improve With Our Famous Guides

• For All Students

The 5 Strategies You Must Be Using to Improve 160+ SAT Points

How to Get a Perfect 1600, by a Perfect Scorer

Series: How to Get 800 on Each SAT Section:

Score 800 on SAT Math

Score 800 on SAT Reading

Score 800 on SAT Writing

Series: How to Get to 600 on Each SAT Section:

Score 600 on SAT Math

Score 600 on SAT Reading

Score 600 on SAT Writing

Free Complete Official SAT Practice Tests

What SAT Target Score Should You Be Aiming For?

15 Strategies to Improve Your SAT Essay

The 5 Strategies You Must Be Using to Improve 4+ ACT Points

How to Get a Perfect 36 ACT, by a Perfect Scorer

Series: How to Get 36 on Each ACT Section:

36 on ACT English

36 on ACT Math

36 on ACT Reading

36 on ACT Science

Series: How to Get to 24 on Each ACT Section:

24 on ACT English

24 on ACT Math

24 on ACT Reading

24 on ACT Science

What ACT target score should you be aiming for?

ACT Vocabulary You Must Know

ACT Writing: 15 Tips to Raise Your Essay Score

How to Get Into Harvard and the Ivy League

How to Get a Perfect 4.0 GPA

How to Write an Amazing College Essay

What Exactly Are Colleges Looking For?

Is the ACT easier than the SAT? A Comprehensive Guide

Should you retake your SAT or ACT?

When should you take the SAT or ACT?

Stay Informed

Get the latest articles and test prep tips!

Looking for Graduate School Test Prep?

Check out our top-rated graduate blogs here:

GRE Online Prep Blog

GMAT Online Prep Blog

TOEFL Online Prep Blog

Holly R. "I am absolutely overjoyed and cannot thank you enough for helping me!”

Introductory essay

Written by the educators who created Mapping and Manipulating the Brain, a brief look at the key facts, tough questions and big ideas in their field. Begin this TED Study with a fascinating read that gives context and clarity to the material.

Here is this mass of jelly, three-pound mass of jelly you can hold in the palm of your hand, and it can contemplate the vastness of interstellar space. It can contemplate the meaning of infinity and it can contemplate itself contemplating on the meaning of infinity. VS Ramachandran

The brain may well be our body's most mysterious organ. Unbelievably complex, utterly fascinating, and notoriously difficult to study, we're left wondering: What exactly does the brain do and how does it do it?

Despite two centuries of intensive research, supported in recent decades by impressive technological advances, answers to many of our questions about the brain are still distant. The reason is easy to appreciate: the brain contains more than ten billion cells — a number equivalent to the total human population on Earth — interacting with each other through about 1,000 times as many connections. Imagine that what's going on in your brain is like a shrunk-down version of the global human population interacting through the Internet. The Internet is hard enough to understand even though we created it; now imagine trying to understand a process of similar complexity without the benefit of knowing how it was generated!

As you listen to these TEDTalks and expand your study of neuroscience through other sources, remember that although we might now know a great deal more about the brain than we did at the start of the 19th century, it's a tiny fraction of what there is to know. Bear in mind that many current ideas may prove wrong. Indeed, it's the excitement of generating and testing, and trying to prove or disprove ideas that might explain the great unknown inside our heads that motivates many research neuroscientists around the world.

A brief history of brain science

The Egyptians wrote the first known descriptions of the brain and its anatomy about 3700 years ago, but another 1200 years elapsed before Greek philosophers of the Hippocratic School identified the brain as the organ responsible for our cognitive functions. Around 400 B.C., Hippocrates declared, "Men ought to know that from the brain, and from the brain only, arise our pleasures, joy, laughter and jests, as well as our sorrows, pains, griefs, and tears." However, not everyone agreed: although Plato and Hippocrates thought that the brain was responsible for sensation, intelligence and mental processes, Aristotle believed it was the heart.

Over the next 2500 years, the work of great European intellectuals including Galen of Bergama, Leonardo da Vinci and Rene Descartes improved our understanding of the brain. By the start of the 19th century, the brain's importance as the organ of perception and higher mental function was beyond doubt.

In the early 1800s, scientists made an important conceptual breakthrough when they hypothesized that different brain functions are carried out in specific and distinct brain regions. Brain regionalization, a concept central to several of the TEDTalks we'll watch, remains an important though controversial component of modern neuroscience.

Some of the initial models of brain regionalization were severely misguided, mainly because they were built on little or no evidence. For example, the Viennese physician Franz Joseph Gall (1758-1828) became convinced for the flimsiest of reasons that each of mankind's mental faculties, including our moral and intellectual capabilities, are each controlled by a separate "organ" within the cerebral hemispheres of the brain. The pseudo-science of phrenology that grew out of Gall's claims gained an enormous popular following in the 19th century; advocates believed that skilled practitioners could feel the lumps and bumps on an individual's skull to gain information about the underlying "organs" and thus fully describe the individual's personality and mental abilities.

Although phrenology is now discredited, the fundamental idea that different functions are localized to different areas of the brain turned out to have merit — even if Gall got the details wrong. The story of phrenology also provides a salutary lesson on the dangers of accepting popular beliefs about aspects of brain function and dysfunction that are difficult to critically evaluate through scientific experimentation. Even today, it's common to find that people think they know more than it's currently possible to know about how and why brains work or go wrong; for example, the causes and cures for various types of mental illness, which may contribute to the social stigma that surrounds these conditions.

Through the late 19th and early 20th centuries, scientists including Pierre Paul Broca, Carl Wernicke, Korbinian Brodmann and Wilder Penfield found credible scientific evidence supporting the subdivision of the brain into discrete areas with different specific functions. Their work was based on studies of patients with localized lesions of the brain, of the anatomical differences between different parts of the brain and of the effects of stimulating discrete brain regions on bodily actions. Together, scientists such as these laid the foundations of modern neuroscience. As you watch the TEDTalks in Mapping and Manipulating the Brain , notice how the speakers reference some of the same approaches used by Broca, Wernicke, Brodmann and Penfield, and how they apply the concepts of brain regionalization and localization of function . Bear in mind, however, that although these concepts are useful, they're also controversial -- more on this below.

How brains are built

Spanish scientist Santiago Ramón Y Cajal (1852-1934) is often thought of as the father of modern neuroscience. Through his extensive and beautiful studies of the microscopic structure of the brain, he discovered that the neuron is the fundamental unit of the nervous system. Since Ramón Y Cajal's breakthrough, scientists have sought to understand how the billions of neurons in the brain are organized to support so many complex functions.

This daunting task would likely be easier if we could follow the process by which the brain is generated, but following brain development is very difficult to do in humans. Thus, we often have to infer how the human brain develops by studying the developing brains of other species, so-called "model organisms" selected for their particular advantages in certain experimental procedures. Aside from helping us to work out how the adult brain functions, research on brain development is a major area in neuroscience for other reasons as well. For example, many conditions like schizophrenia and autism can be traced back to abnormalities in earlier brain development.

The great molecular, structural and functional diversity of brain cells, along with their specializations and precise interactions, are acquired in an organized way through processes that build on differences between the relatively small numbers of cells in the early embryo. As more and more cells are generated in a growing organism, new cells diversify in specific ways as a result of interactions with pre-existing cells, continually adding to the organism's complexity in a highly regulated manner. To understand how brains develop we need to know how their cells develop in specific and reproducible ways as a result of their own internal mechanisms interacting with an expanding array of stimuli from outside the cell.

Since, as discussed above, regionalization is a prominent organizing feature in mature brains, when and how is it established during brain development? Some of the most exciting research on brain development in recent years has focused on this question.

For neurons to develop regional identities, they must possess or acquire information on where they are located within the brain so that they can take on the appropriate specializations. How neurons gain positional information has been one of the most prominent themes in developmental neuroscience in the last 50 years or so, as indeed it has in the broader field of developmental biology (positional identity is required not only by brain cells).

The model that has dominated current thinking was famously elaborated in the 1960s by Lewis Wolpert in his French flag analogy. Here, a signal produced by a group of organizer cells diffuses from its source through a surrounding field of cells. In so doing, it forms a concentration gradient with more of the signal present in areas closer to the source. Cells respond to the concentration of this signal. In Wolpert's French Flag analogy, they become blue, white or red (in reality, they would become cells of different types, not different colors). Close to the source, cells receive signals above the highest threshold (to become blue, or type 1). Beyond this, cells respond to a lower dose (to become white, or type 2) while farther still cells do not receive enough of the signal to respond (and become red, or type 3). Here the model is expressed in terms of three outcomes, but there might be a different number of outcomes depending on the locations and/ or stages of development. The important point is that cells can work out where they are based on the level of signal they receive and they respond accordingly by developing different attributes.

Beyond Wolpert's basic model, the issue of how brain regionalization develops is an important question and we have relatively few answers. Regional specification is a prerequisite for the development of the connections that must link each region of the brain in a stereotypical and highly precise way (but allowing room for plasticity at a fine level). How these trillions of connections are made is another of life's great mysteries.

The connectome and connectionism

Since Ramón Y Cajal's first description of the neuron, scientists have vastly expanded our understanding of the structure and function of these individual building blocks of the brain. However, as Tim Berners-Lee comments, this is just the first step in understanding how our brains really work: "There are billions of neurons in our brains, but what are neurons? Just cells. The brain has no knowledge until connections are made between neurons. All that we know, all that we are, comes from the way our neurons are connected."

You'll hear about the "connectome" in Sebastian Seung's TEDTalk. The suffix "–ome" is used with increasing frequency to indicate a complete collection of whatever units are specified in the first part of the word, such as genes (hence genome), proteins (proteome) or connections (connectome). The connectome of the human brain is bewildering in its complexity, but the development of new brain imaging methods has catalyzed the first serious attempts to map it in living brains. At present, the resolution of imaging methods that can be applied to living brains isn't sufficient to follow individual connections (called axons). In these TEDTalks you'll hear about an attempt to come at the problem from the other direction, using very high resolution imaging of non-living brain tissue to reconstruct the ultramicroscopic anatomy of connections around individual cells. The extent to which these approaches are likely to succeed remains controversial.

The theory known as connectionism addresses a somewhat different matter within the field of brain organization: the relationship between connectivity and function. Essentially, the idea is that higher mental processes such as object recognition, memory and language result from the activity of the connections between areas of the brain rather than the activity of specific discrete regions. Whereas connectionists would agree that primary sensory and motor functions (i.e. responses to sensory stimuli and the activation of movements) are strongly localized to defined areas within the brain, they argue that this applies less clearly at higher cognitive levels. The theory emphasizes the relationship between connected brain areas and the function of the brain as a whole, with all parts having the potential to contribute to cognitive function. You should appreciate, therefore, that there is as yet no accepted view of the extent to which our higher mental functions are localized to particular parts of the brain. It is worth remembering this as you listen to the TEDTalks; keep an open mind on these truly fascinating issues.

Ways of studying brain function

In these TEDTalks, you're going to hear about some of the ways in which we can work out what the human brain does and how it does it. One longstanding approach is to examine what happens when people suffer brain lesions. Phineas Gage, a Vermont railroad worker, provides one spectacular historical example from 1848. Gage was packing gunpowder into a hole when it exploded, blowing the tamping rod through the front of his brain. Astonishingly, he survived and recovered, but those closest to him claimed that he had a very different personality. From this example, scientists hypothesized that elements of human personality are localized to the frontal lobes.

In Jill Bolte Taylor's TEDTalk, you'll hear how Taylor's own stroke provides further evidence for localization of brain function. A few words of caution, however: when we study the effects of a lesion on the brain, we're really learning about what the rest of the brain does without the damaged part, which is not quite the same as what the damaged structure itself does. Maybe this seems rather subtle, but in some cases it becomes important, for example if a lesion causes other parts of the brain to alter what they do.

You'll also hear about powerful techniques for observing the activity of living brains, for example using functional magnetic resonance imaging (FMRI; see the TEDTalk by Oliver Sacks). And you'll hear about methods for looking at the fine structure of neurons in post-mortem material, as in Sebastian Seung's TEDTalk. All have advantages and limitations, but together they give ever- increasing insight into the workings of the human mind.

Let's begin the TEDTalks with neuroanatomist Jill Bolte Taylor, who provides a basic overview of the brain and describes what she learned firsthand about its structure and function when at age 37 she suffered a massive hemorrhage in the left hemisphere of her brain.

Jill Bolte Taylor

My stroke of insight, relevant talks.

VS Ramachandran

3 clues to understanding your brain.

Oliver Sacks

What hallucination reveals about our minds.

Sebastian Seung

I am my connectome.

Christopher deCharms

A look inside the brain in real time.

A light switch for neurons

Rebecca Saxe

How we read each other's minds.

The human brain, explained

Learn about the most complex organ in the human body, from its structure to its most common disorders.

Here’s something to wrap your mind around: The human brain is more complex than any other known structure in the universe . Weighing in at three pounds, on average, this spongy mass of fat and protein is made up of two overarching types of cells—called glia and neurons—and it contains many billions of each. Neurons are notable for their branch-like projections called axons and dendrites, which gather and transmit electrochemical signals. Different types of glial cells provide physical protection to neurons and help keep them, and the brain, healthy.

Together, this complex network of cells gives rise to every aspect of our shared humanity. We could not breathe, play, love, or remember without the brain.

Anatomy of the brain

The cerebrum is the largest part of the brain , accounting for 85 percent of the organ's weight. The distinctive, deeply wrinkled outer surface is the cerebral cortex. It's the cerebrum that makes the human brain—and therefore humans—so formidable. Animals such as elephants, dolphins, and whales actually have larger brains, but humans have the most developed cerebrum. It's packed to capacity inside our skulls, with deep folds that cleverly maximize the total surface area of the cortex .

The cerebrum has two halves, or hemispheres, that are further divided into four regions, or lobes. The frontal lobes, located behind the forehead, are involved with speech, thought, learning, emotion, and movement. Behind them are the parietal lobes, which process sensory information such as touch, temperature, and pain. At the rear of the brain are the occipital lobes, dealing with vision. Lastly, there are the temporal lobes, near the temples, which are involved with hearing and memory.

The second-largest part of the brain is the cerebellum , which sits beneath the back of the cerebrum. It plays an important role in coordinating movement, posture, and balance.

The third-largest part is the diencephalon, located in the core of the brain. A complex of structures roughly the size of an apricot, its two major sections are the thalamus and hypothalamus. The thalamus acts as a relay station for incoming nerve impulses from around the body that are then forwarded to the appropriate brain region for processing. The hypothalamus controls hormone secretions from the nearby pituitary gland. These hormones govern growth and instinctual behaviors, such as when a new mother starts to lactate. The hypothalamus is also important for keeping bodily processes like temperature, hunger, and thirst balanced.

For Hungry Minds

Seated at the organ's base, the brain stem controls reflexes and basic life functions such as heart rate, breathing, and blood pressure. It also regulates when you feel sleepy or awake and connects the cerebrum and cerebellum to the spinal cord.

The brain is extremely sensitive and delicate, and so it requires maximum protection, which is provided by the hard bone of the skull and three tough membranes called meninges. The spaces between these membranes are filled with fluid that cushions the brain and keeps it from being damaged by contact with the inside of the skull.

Blood-brain barrier

Want more proof that the brain is extraordinary? Look no further than the blood-brain barrier. The discovery of this unique feature dates to the 19th century, when various experiments revealed that dye, when injected into the bloodstream, colored all of the body’s organs except the brain and spinal cord. The same dye, when injected into the spinal fluid, tinted only the brain and spinal cord.

You May Also Like

Can positive thinking prolong your life? Science says yes

How to get high on your own hormones—naturally

Can you really sweat out toxins?

This led scientists to learn that the brain has an ingenious, protective layer. Called the blood-brain barrier, it’s made up of special, tightly bound cells that together function as a kind of semi-permeable gate throughout most of the organ . It keeps the brain environment safe and stable by preventing some toxins, pathogens, and other harmful substances from entering the brain through the bloodstream, while simultaneously allowing oxygen and vital nutrients to pass through.

Health conditions of the brain

Of course, when a machine as finely calibrated and complex as the brain gets injured or malfunctions, problems arise. One in five Americans suffers from some form of neurological damage , a wide-ranging list that includes stroke, epilepsy, and cerebral palsy, as well as dementia.

Alzheimer’s disease , which is characterized in part by a gradual progression of short-term memory loss, disorientation, and mood swings, is the most common cause of dementia . It is the sixth leading cause of death in the United States, and the number of people diagnosed with it is growing. Worldwide, some 50 million people suffer from Alzheimer’s or some form of dementia. While there are a handful of drugs available to mitigate Alzheimer’s symptoms, there is no cure. Researchers across the globe continue to develop treatments that one day might put an end to the disease’s devasting effects.

Far more common than neurological disorders, however, are conditions that fall under a broad category called mental illness . Unfortunately, negative attitudes toward people who suffer from mental illness are widespread. The stigma attached to mental illness can create feelings of shame, embarrassment, and rejection, causing many people to suffer in silence. In the United States, where anxiety disorders are the most common forms of mental illness, only about 40 percent of sufferers receive treatment. Anxiety disorders often stem from abnormalities in the brain’s hippocampus and prefrontal cortex.

Attention-deficit/hyperactivity disorder, or ADHD , is a mental health condition that also affects adults but is far more often diagnosed in children. ADHD is characterized by hyperactivity and an inability to stay focused. While the exact cause of ADHD has not yet been determined, scientists believe that it may be linked to several factors, among them genetics or brain injury. Treatment for ADHD may include psychotherapy as well as medications. The latter can help by increasing the brain chemicals dopamine and norepinephrine, which are vital to thinking and focusing.

Depression is another common mental health condition. It is the leading cause of disability worldwide and is often accompanied by anxiety. Depression can be marked by an array of symptoms, including persistent sadness, irritability, and changes in appetite. The good news is that in general, anxiety and depression are highly treatable through various medications—which help the brain use certain chemicals more efficiently—and through forms of therapy.

Related Topics

• NEUROSCIENCE

How much of a role does genetics play in obesity?

The 11 most astonishing scientific discoveries of 2023

Why do some say natural deodorants are better—and are the claims accurate?

This is why getting scared can feel so good

Nature really is good medicine. Science can explain why.

• Environment

History & Culture

• History & Culture
• History Magazine
• Gory Details
• Mind, Body, Wonder
• Paid Content
• Terms of Use
• Privacy Policy
• Your US State Privacy Rights
• Children's Online Privacy Policy
• Interest-Based Ads
• About Nielsen Measurement
• Do Not Sell or Share My Personal Information
• Nat Geo Home
• Attend a Live Event
• Book a Trip
• Inspire Your Kids
• Shop Nat Geo
• Visit the D.C. Museum
• Learn About Our Impact
• Support Our Mission
• Advertise With Us
• Customer Service
• Renew Subscription
• Manage Your Subscription
• Work at Nat Geo
• Sign Up for Our Newsletters
• Contribute to Protect the Planet

Copyright © 1996-2015 National Geographic Society Copyright © 2015-2024 National Geographic Partners, LLC. All rights reserved

An official website of the United States government

The .gov means it's official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings
• Browse Titles

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

StatPearls [Internet].

Physiology, brain.

Kenia A. Maldonado ; Khalid Alsayouri .

Affiliations

Last Update: March 17, 2023 .

• Introduction

The human brain is perhaps the most complex of all biological systems, with the mature brain composed of more than 100 billion information-processing cells called neurons. [1]  The brain is an organ composed of nervous tissue that commands task-evoked responses, movement, senses, emotions, language, communication, thinking, and memory. The three main parts of the human brain are the cerebrum, cerebellum, and brainstem. 

The cerebrum is divided into the right and left hemispheres and is the largest part of the brain. It contains folds and convolutions on its surface, with the ridges found between the convolutions called gyri and the valleys between the gyri called sulci (plural of sulcus). If the sulci are deep, they are called fissures. Both cerebral hemispheres have an outer layer of gray matter called the cerebral cortex and inner subcortical white matter.

Located in the posterior cranial fossa, above the foramen magnum, the cerebellum's primary function is to modulate motor coordination, posture, and balance. It is comprised of the cerebellar cortex and deep cerebellar nuclei, with the cerebellar cortex being made up of three layers; the molecular, Purkinje, and granular layers. The cerebellum connects to the brainstem via cerebellar peduncles.

The brainstem contains the midbrain, pons, and medulla. It is located anterior to the cerebellum, between the base of the cerebrum and the spinal cord.

• Issues of Concern

Studies of brain function have focused on analyzing the variations of the electrical activity produced by the application of sensory stimuli. However, it is also essential to study additional features and functions of the brain, including information processing and responding to environmental demands. [2]

The brain works precisely, making connections, and is a deeply divided structure that has remained not entirely explained or examined. [3]  Although researchers have made significant progress in experimental techniques, the human cognitive function that emerges from neuronal structure and dynamics is not entirely understood. [4]

• Cellular Level

At the beginning of the forebrain formation, the neuroepithelial cells undergo divisions at the inner surface of the neural tube to generate new progenitors. These dividing neuroepithelial cells transform and diversify, leading to radial glial cells (RGCs).

RGCs also work as progenitors with the capacity to regenerate themselves and produce other types of progenitors, neurons, and glial cells. [5]  RGCs have long processes that connect with the neuroepithelium and function as a guide for the migration of neuron cells to ensure that neurons find their resting place, mature, and send out axons and dendrites to participate directly in synapses and electrical signaling. Neurons get produced along with glial cells; glial cells bring support and create an enclosed environment in which neurons can perform their functions.

Glial cells (astrocytes, oligodendrocytes, microglial cells) have well-known roles, which include: keeping the ionic medium of neurons, controlling the rate of nerve signal propagation and synaptic action by regulating the uptake of neurotransmitters, providing a platform for some aspects of neural development, and aiding in recovery from neural damage.

Gray matter is the main component of the central nervous system (CNS) and consists of neuronal cell bodies, dendrites, myelinated and unmyelinated axons, glial cells, synapses, and capillaries. The cerebral cortex is made up of layers of neurons that constitute the gray matter of the brain. The subcortical (beneath the cortex) area is primarily white matter composed of myelinated axons with fewer quantities of cell bodies when compared to gray matter.

Although neurons can have different morphologies, they all contain four common regions: the cell body, the dendrites, the axon, and the axon terminals, each with its respective functions.

The cell body contains a nucleus where proteins and membranes are synthesized. These proteins travel through microtubules down to the axons and terminals via a mechanism known as anterograde transport. In retrograde transport, damaged membranes and organelles travel from the axon toward the cell body along axonal microtubules. Lysosomes are only present in the cell body and are responsible for containing and degrading damaged material. The axon is a thin continuation of a neuron that allows electrical impulses to be sent from neuron to neuron.

Astrocytes occupy 25% of the total brain volume and are the most abundant glial cells. [6]  They are classified into two main groups: protoplasmic and fibrous. Protoplasmic astrocytes appear in gray matter and have several branches that contact both synapses and blood vessels. Fibrous astrocytes are present in the white matter and have long fiber-like processes that contact the nodes of Ranvier and the blood vessels. Astrocytes use their connections to vessels to titrate blood flow in synaptic activity responses. Astrocytic endfeet, which forms tight junctions between endothelial cells and the basal lamina, gives rise to the formation of the blood-brain barrier (BBB). [7]

The primary function of oligodendrocytes is to make myelin, a proteolipid critical in maintaining electrical impulse conduction and maximizing velocity. Myelin is located in segments separated by nodes of Ranvier, and their function is equivalent to those of Schwan cells in the peripheral nervous system.

The macrophage populations of the CNS include microglia, perivascular macrophages, meningeal macrophages, macrophages of the circumventricular organs (CVO), and the microglia of the choroid plexus. Microglia are phagocytic cells representing the immune and support system of the CNS and are the most abundant cells of the choroid plexus. [8]

• Development

Human brain development starts with the neurulation process from the ectodermic layer of the embryo and takes, on average, 20 to 25 years to mature. [9]  It occurs in a sequential and organized manner beginning with the neural tube formation at the third or fourth week of gestation. This is followed by cell migration and proliferation that leads to the folding of the cerebral cortex to increase its size and surface area, creating a more complex structure. Failure of this migration and proliferation leads to a smooth brain without sulci or gyri, termed lissencephaly. [10] At birth, the general architecture of the brain is mostly complete, and by the age of 5 years, the total brain volume is about 95% of its adult size. Generally, the white matter increases with age, while the gray matter decreases with age.

The most prominent white matter structure of the brain, the corpus callosum, increases by approximately 1.8% per year between the ages of 3 and 18 years. [11]  The corpus callosum conjugates the activity of the right and left hemispheres and allows for the progress of higher-order cognitive abilities.

Gray matter in the frontal lobe undergoes continued structural development reaching its maximal volume at 11 to 12 years of age before slowing down during adolescence and early adulthood. The gray matter in the temporal lobe follows a similar development pattern, reaching its maximum size at 16 to 17 years of age with a slight decline afterward. [12]

Below is a list of the brain vesicles and the areas of the brain which develop from them. [13]

Prosencephalon (Forebrain)

• Cerebral cortex
• Basal ganglia (caudate nucleus, putamen, and globus pallidus)
• Hippocampus
• Lateral ventricles
• Hypothalamus
• Epithalamus (pineal gland)
• Subthalamus
• Posterior pituitary
• Optic nerve
• Third ventricle

Mesencephalon (midbrain)

• Cerebral aqueduct

Rhombencephalon (hindbrain)

• Fourth ventricle (rostral)
• Fourth ventricle (caudal)
• Organ Systems Involved

The brain and the spinal cord comprise the central nervous system (CNS). The peripheral nervous system (PNS) subdivides into the somatic nervous system (SNS) and the autonomic nervous system (ANS). The SNS consists of peripheral nerve fibers that collect sensory information to the CNS and motor fibers that send information from the CNS to skeletal muscle. The ANS functions to control the smooth muscle of the viscera and glands and consists of the sympathetic nervous system (SNS), the parasympathetic nervous system (PaNS), and the enteric nervous system (ENS).

Nerves from the brain connect with multiple parts of the head and body, leading to various voluntary and involuntary functions. The ANS drives basic functions that control unconscious activities such as breathing, digestion, sweating, and trembling.

The ENS provides the intrinsic innervation of the gastrointestinal system and is the most neurochemically diverse branch of the PNS. [14]  Neurotransmitters such as norepinephrine, epinephrine, dopamine, and serotonin have recently been a topic of interest due to their roles in gut physiology and CNS pathophysiology, as they aid in regulating gut blood flow, motility, and absorption. [15]

The cerebrum controls motor and sensory information, conscious and unconscious behaviors, feelings, intelligence, and memory. The left hemisphere controls speech and abstract thinking (the ability to think about things that are not present). In contrast, the right hemisphere controls spatial thinking (thinking that finds meaning in the shape, size, orientation, location, and phenomena).

The motor and sensory neurons descending from the brain cross to the opposite side in the brainstem. This crossing means that the right side of the brain controls the motor and sensory functions of the left side of the body, and the left side of the brain controls the motor and sensory functions of the right side of the body. Hence, a stroke affecting the left brain hemisphere, for example, will exhibit motor and sensory deficits on the right side of the body.

Sensory neurons bring sensory input from the body to the thalamus, which then relays this sensory information to the cerebrum. For example, hunger, thirst, and sleep are under the control of the hypothalamus.

The cerebrum is composed of four lobes:

• Frontal lobe: Responsible for motor function, language, and cognitive processes, such as executive function, attention, memory, affect, mood, personality, self-awareness, and social and moral reasoning. [16]  The Broca area is located in the left frontal lobe and is responsible for the production and articulation of speech.
• Parietal lobe: Responsible for interpreting vision, hearing, motor, sensory, and memory functions. 
• Temporal lobe: In the left temporal lobe, the Wernicke area is responsible for understanding spoken and written language. The temporal lobe is also an essential part of the social brain, as it processes sensory information to retain memories, language, and emotions. [17]  The temporal lobe also plays a significant role in hearing and spatial and visual perception.
• Occipital lobe: The visual cortex is located in the occipital lobe and is responsible for interpreting visual information.

The cerebellum controls the coordination of voluntary movement and receives sensory information from the brain and spinal cord to fine-tune the precision and accuracy of motor activity. The cerebellum also aids in various cognitive functions such as attention, language, pleasure response, and fear memory. [18]

The brainstem acts as a bridge that connects the cerebrum and cerebellum to the spinal cord. The brainstem houses the principal centers which perform autonomic functions such as breathing, temperature regulation, respiration, heart rate, wake-sleep cycles, coughing, sneezing, digestion, vomiting, and swallowing. The brainstem contains both white and gray matter. The white matter consists of fiber tracts (neuronal cell axons) traveling down from the cerebral cortex for voluntary motor function and up from the spinal cord and peripheral nerves, allowing somatosensory information to travel to the highest parts of the brain. [19]

The brain represents 2% of the human body weight and consumes 15% of the cardiac output and 20% of total body oxygen. The resting brain consumes 20% of the body's energy supply. When the brain performs a task, the energy consumption increases by an additional 5%, proving that most of the brain's energy consumption gets used for intrinsic functions.

The brain uses glucose as its principal source of energy. During low glucose states, the brain utilizes ketone bodies as its primary energy source. During exercise, the brain can use lactate as a source of energy.

In the developing brain, neurons follow molecular signals from regulatory cells like astrocytes to determine their location, the type of neurotransmitter they will secrete, and with which neurons they will communicate, leading to the formation of a circuit between neurons that will be in place during adulthood. In the adult brain, developed neurons fit in their corresponding place and develop axons and dendrites to connect with the neighboring neurons. [20]

Neurons communicate via neurotransmitters released into the synaptic space, a 20 to 50-nanometer area between neurons. The neuron that releases the neurotransmitter into the synaptic space is called the presynaptic neuron, and the neuron that receives the neurotransmitter is called the postsynaptic neuron. An action potential in the presynaptic neuron leads to calcium influx and the subsequent release of neurotransmitters from their storage vesicle into the synaptic space. The neurotransmitter then travels to the postsynaptic neuron and binds to receptors to influence its activity. Neurotransmitters are rapidly removed from the synaptic space by enzymes. [21]

The oligodendrocytes in the CNS produce myelin. Myelin forms insulating sheaths around axons to allow the swift travel of electrical impulses through the axons. The nodes of Ranvier are gaps in the myelin sheath of axons, allowing sodium influx into the axon to help maintain the speed of the electrical impulse traveling through the axon. This transmission is called saltatory nerve conduction, the "jumping" of electrical impulses from one node to another. It ensures that electrical signals do not lose their velocity and can propagate long distances without signal deterioration. [22]

• Related Testing

Functional magnetic resonance imaging (fMRI) can track the effects of neural activity and the energy that the brain consumes by measuring components of the metabolic chain. Other techniques, such as single-photon emission computed tomography (SPECT), study cerebral blood flow and neuroreceptors. Positron emission tomography (PET) assesses the glucose metabolism of the brain. [23]  Electroencephalography (EEG) records the brain's electrical activity and is very useful for detecting various brain disorders. Advancements in these techniques have enabled a broader vision and objective perceptions of mental disorders, leading to improved diagnosis, treatment, and prognosis.

• Pathophysiology

Injury to the brain stimulates the proliferation of astrocytes, an immunological response to neurodegenerative disorders called "reactive gliosis." [24]  Damage to neural tissue promotes molecular and morphological changes and is essential in the upregulation of the glial fibrillary acidic protein (GFAP). On the other hand, epidermal growth factor receptor (EGFR) allows the transition from non-reactive to reactive astrocytes, and its inhibition improves axonal regeneration and rapid recovery. This means that when astrocytes are reactive, they proliferate and hypertrophy, leading to glial scar formation.

The microglia represent the immune and support system of the CNS. They are neuroprotective in the young brain but can react abnormally to stimuli in the aged brain and become neurotoxic and destructive, leading to neurodegeneration. [25]  As the brain ages, microglia acquire an increasingly inflammatory and cytotoxic phenotype, generating a hazardous environment for neurons. [26]  Hence, aging is the most critical risk factor for developing neurodegenerative diseases.

The brain is surrounded by cerebrospinal fluid and is isolated from the bloodstream by the blood-brain barrier (BBB). In cases like infectious meningitis and meningoencephalitis, acute inflammation causes a breakdown of the BBB, leading to the influx of blood-borne immune cells into the CNS. In other inflammatory brain disorders such as Alzheimer disease (AD), Parkinson disease (PD), Huntington disease (HD), or X-linked adrenoleukodystrophy, the primary insult is due to degenerative or metabolic processes, and there is no breakdown of the BBB. [27]

Oligodendrocyte loss can occur due to the production of reactive oxygen species or the activation of inflammatory cytokines, causing decreased myelin production and leading to conditions such as multiple sclerosis (MS). [22]

Disturbances in the neurotransmitter systems are related to these substances' production, release, reuptake, or receptor impairments and can cause neurologic or psychiatric disorders. Glutamate is the brain's most abundant excitatory neurotransmitter, while GABA is the primary inhibitory transmitter. Glycine has a similar inhibitory action in the posterior parts of the brain. Acetylcholine aids in processes such as muscle stimulation at the neuromuscular junction (NMJ), digestion, arousal, salivation, and level of attention. Dopamine is involved in the reward and motivational component, motor control, and the regulation of prolactin release. Serotonin influences mood, feelings of happiness, and anxiety. Norepinephrine is involved in arousal, alertness, vigilance, and attention. 

Cerebral oxygen delivery and consumption rates are ten times higher than global body values. [28]  Blood glucose represents the primary energy source for the brain, and the BBB is highly permeable to it. During low glucose states, the body has developed multiple ways to keep blood glucose within the normal range. As the level drops below 80 mg/dL, pancreatic beta-cells decrease insulin secretion to avoid further glucose decrease. If glucose drops further, pancreatic alpha-cells secrete glucagon, and the adrenal medulla releases epinephrine. Glucagon and epinephrine increase blood glucose levels. Cortisol and growth hormone also act to increase glucose, but they depend on the presence of glucagon and epinephrine to work.

• Clinical Significance

Damage to the Cerebrum

• Frontal lobe -  Damage to the frontal lobe causes interruption of the higher functioning brain processes, including social behavior, planning, motivation, and speech production. Individuals with frontal lobe damage may be unable to regulate their emotions, have meaningful or appropriate social interactions, maintain their past personality traits, or make difficult decisions. [29]
• Temporal lobe - The Wernicke area is located in the superior temporal gyrus in an individual's dominant hemisphere, which is the left hemisphere for 95% of people. Damage to the left (dominant) temporal lobe can lead to Wernicke aphasia. This is typically referred to as "word salad" speech, where the patient will speak fluently, but their words and sentences will lack meaning. [30]  Damage to the right (non-dominant) temporal lobe may lead to persistent talking and deficits in nonverbal memory, processing certain aspects of sound or music (tone, rhythm, pitch), and facial recognition (prosopagnosia).
• Parietal lobe -  Damage to the frontal aspect of the parietal lobe may lead to impaired sensation and numbness on the contralateral side of the body. An individual may have difficulty recognizing texture and shape and may be unable to identify a sensation and its location on their body. Damage to the middle aspect of the parietal lobe can lead to right-left disorientation and difficulty with proprioception. Damage to the non-dominant (right) parietal lobe may lead to apraxia (difficulty with performing purposeful motions such as combing hair or brushing teeth) and difficulty with spatial orientation and navigation (they may get lost in a once familiar area). Patients with non-dominant parietal lobe damage, usually from a middle cerebral artery stroke, may neglect the side opposite of the brain damage (usually the left side), which may manifest as only shaving the right side of their face or drawing a clock with all of the numbers on the right side of the circle. [31]
• Occipital lobe -  Damage to the occipital lobe may lead to visual defects, color agnosia (inability to identify colors), movement agnosia (difficulty recognizing object movements), hallucinations, illusions, and the inability to recognize written words (word blindness). 

Damage to the Cerebellum

Damage to the cerebellum can lead to ataxia, dysmetria, dysarthria, scanning speech, dysdiadochokinesis, tremor, nystagmus, and hypotonia. To test for possible cerebellar dysfunction, a bedside neurologic exam is commonly the first step. This exam may include the Romberg test, heel-to-shin test, finger-to-nose test, and rapid alternating movement test. [32]

Damage to the Brainstem

Damage to the brainstem may present as muscle weakness, visual changes, dysphagia, vertigo, speech impairment, pupil abnormalities, insomnia, respiratory depression, or death.

Neurodegenerative Diseases

Neuronal degeneration worsens with age and can affect different areas of the brain leading to movement, memory, and cognition problems.

Parkinson disease (PD) occurs due to the degeneration of the neurons that synthesize dopamine, leading to motor function deficits. Alzheimer disease (AD) occurs due to abnormally folded protein deposition in the brain leading to neuronal degeneration. Huntington disease occurs due to a genetic mutation that increases the production of the neurotransmitter glutamate. Excessive amounts of glutamate lead to the death of neurons in the basal ganglia producing movement, cognitive, and psychiatric deficits. Vascular dementia occurs due to the death of neurons resulting from the interruption of blood supply.

Although neurodegenerative diseases are not classically caused by disturbed metabolism, research has shown that there is a reduction in glucose metabolism in Alzheimer disease. [33]

Demyelinating Diseases

Demyelinating diseases result from damage to the myelin sheath that covers the nerve cells in the white matter of the brain, spinal cord, and optic nerves. For example, multiple sclerosis and leukodystrophies are a consequence of oligodendrocyte damage.

A stroke is caused by an interruption in the blood supply to the brain, which may ultimately lead to neuronal death. This condition can result in one of several neurological problems depending on the affected region.

Brain Death

Neurologic evaluation of brain death is a complicated process that non-specialists and families might misunderstand. [34]  Brain death is the complete and irreversible loss of brain activity, including the brainstem. It requires verification through well-established clinical protocols and the support of specialized tests.

Hypoglycemia

Glucose is the primary energy source responsible for maintaining brain metabolism and function. The most significant amount of glucose is used for information processing by neurons. [35]  The brain requires a continuous supply of glucose as it has limited glucose reserves. CNS symptoms and signs of hypoglycemia include focal neurological deficits, confusion, stupor, seizure, cognitive impairment, or death.

• Review Questions
• Access free multiple choice questions on this topic.
• Comment on this article.

Brain, Encephalon, Connections of the several parts of the brain, Cerebrum, Cerebellum, Pons, Cerebral; Superior; Middle; Inferior Peduncle, Medulla oblongata Henry Vandyke Carter, Public Domain, via Wikimedia Commons

The Fore-brain or Prosencephalon, Mesal aspect of a brain sectioned in the median sagittal plane, Foramen of Monro, Middle commissure, Taenia thalami, Habenular commissure, Genu, Callosum, Fornix, Septum Lucidum, Plenum, Pons, Oblongata, Thalamus Henry (more...)

Areas of localization on lateral surface of hemisphere. Motor area in red, Area of general sensations in blue, Auditory area in green, Visual area in yellow, Brain, Neurology Henry Vandyke Carter, Public Domain, via Wikimedia Commons

Pathways from the Brain to the Spinal Cord, The motor tract, Anterior nerve roots, Anterior and Lateral cerebrospinal Fasciculus, Decussation of pyramids, Geniculate fibers, Internal capsule, Motor area of cortex Henry Vandyke Carter, Public Domain, via (more...)

Homonculus: sensory & motor Image courtesy S. Bhimji MD

Disclosure: Kenia Maldonado declares no relevant financial relationships with ineligible companies.

Disclosure: Khalid Alsayouri declares no relevant financial relationships with ineligible companies.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

• Cite this Page Maldonado KA, Alsayouri K. Physiology, Brain. [Updated 2023 Mar 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

In this Page

Bulk download.

• Bulk download StatPearls data from FTP

Related information

• PMC PubMed Central citations
• PubMed Links to PubMed

Similar articles in PubMed

• Brainstem Stroke. [StatPearls. 2024] Brainstem Stroke. Gowda SN, Munakomi S, De Jesus O. StatPearls. 2024 Jan
• Neuroanatomy, Medulla Oblongata. [StatPearls. 2024] Neuroanatomy, Medulla Oblongata. Iordanova R, Reddivari AKR. StatPearls. 2024 Jan
• Lower Genitourinary Trauma. [StatPearls. 2024] Lower Genitourinary Trauma. Tullington JE, Blecker N. StatPearls. 2024 Jan
• Review Anatomy of the brainstem: a gaze into the stem of life. [Semin Ultrasound CT MR. 2010] Review Anatomy of the brainstem: a gaze into the stem of life. Angeles Fernández-Gil M, Palacios-Bote R, Leo-Barahona M, Mora-Encinas JP. Semin Ultrasound CT MR. 2010 Jun; 31(3):196-219.
• Review Physiology of the cerebellum. [Handb Clin Neurol. 2018] Review Physiology of the cerebellum. D'Angelo E. Handb Clin Neurol. 2018; 154:85-108.

Recent Activity

• Physiology, Brain - StatPearls Physiology, Brain - StatPearls

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

Connect with NLM

National Library of Medicine 8600 Rockville Pike Bethesda, MD 20894

Web Policies FOIA HHS Vulnerability Disclosure

Help Accessibility Careers

Parts of the Brain Involved with Memory

Learning objectives.

• Explain the brain functions involved in memory; recognize the roles of the hippocampus, amygdala, and cerebellum in memory

Are memories stored in just one part of the brain, or are they stored in many different parts of the brain? Karl Lashley began exploring this problem, about 100 years ago, by making lesions in the brains of animals such as rats and monkeys. He was searching for evidence of the engram : the group of neurons that serve as the “physical representation of memory” (Josselyn, 2010). First, Lashley (1950) trained rats to find their way through a maze. Then, he used the tools available at the time—in this case a soldering iron—to create lesions in the rats’ brains, specifically in the cerebral cortex. He did this because he was trying to erase the engram, or the original memory trace that the rats had of the maze.

Lashley did not find evidence of the engram, and the rats were still able to find their way through the maze, regardless of the size or location of the lesion. Based on his creation of lesions and the animals’ reaction, he formulated the equipotentiality hypothesis : if part of one area of the brain involved in memory is damaged, another part of the same area can take over that memory function (Lashley, 1950). Although Lashley’s early work did not confirm the existence of the engram, modern psychologists are making progress locating it. Eric Kandel, for example, spent decades working on the synapse, the basic structure of the brain, and its role in controlling the flow of information through neural circuits needed to store memories (Mayford, Siegelbaum, & Kandel, 2012).

Many scientists believe that the entire brain is involved with memory. However, since Lashley’s research, other scientists have been able to look more closely at the brain and memory. They have argued that memory is located in specific parts of the brain, and specific neurons can be recognized for their involvement in forming memories. The main parts of the brain involved with memory are the amygdala, the hippocampus, the cerebellum, and the prefrontal cortex (Figure 1).

First, let’s look at the role of the amygdala in memory formation. The main job of the amygdala is to regulate emotions, such as fear and aggression. The amygdala plays a part in how memories are stored because storage is influenced by stress hormones. For example, one researcher experimented with rats and the fear response (Josselyn, 2010). Using Pavlovian conditioning, a neutral tone was paired with a foot shock to the rats. This produced a fear memory in the rats. After being conditioned, each time they heard the tone, they would freeze (a defense response in rats), indicating a memory for the impending shock. Then the researchers induced cell death in neurons in the lateral amygdala, which is the specific area of the brain responsible for fear memories. They found the fear memory faded (became extinct). Because of its role in processing emotional information, the amygdala is also involved in memory consolidation: the process of transferring new learning into long-term memory. The amygdala seems to facilitate encoding memories at a deeper level when the event is emotionally arousing.

Link to Learning

In this TED Talk called “A Mouse. A Laser Beam. A Manipulated Memory,” Steve Ramirez and Xu Liu from MIT talk about using laser beams to manipulate fear memory in rats. Find out why their work caused a media frenzy once it was published in Science .

Hippocampus

Another group of researchers also experimented with rats to learn how the hippocampus functions in memory processing. They created lesions in the hippocampi of the rats, and found that the rats demonstrated memory impairment on various tasks, such as object recognition and maze running. They concluded that the hippocampus is involved in memory, specifically normal recognition memory as well as spatial memory (when the memory tasks are like recall tests) (Clark, Zola, & Squire, 2000). Another job of the hippocampus is to project information to cortical regions that give memories meaning and connect them with other connected memories. It also plays a part in memory consolidation: the process of transferring new learning into long-term memory.

Injury to this area leaves us unable to process new declarative memories. One famous patient, known for years only as H. M., had both his left and right temporal lobes (hippocampi) removed in an attempt to help control the seizures he had been suffering from for years (Corkin, Amaral, González, Johnson, & Hyman, 1997). As a result, his declarative memory was significantly affected, and he could not form new semantic knowledge. He lost the ability to form new memories, yet he could still remember information and events that had occurred prior to the surgery.

View this Slate video for a closer look at how memory works, as well as how researchers are now studying H. M.’s brain.

Cerebellum and Prefrontal Cortex

Although the hippocampus seems to be more of a processing area for explicit memories, you could still lose it and be able to create implicit memories (procedural memory, motor learning, and classical conditioning), thanks to your cerebellum. For example, one classical conditioning experiment is to accustom subjects to blink when they are given a puff of air. When researchers damaged the cerebellums of rabbits, they discovered that the rabbits were not able to learn the conditioned eye-blink response (Steinmetz, 1999; Green & Woodruff-Pak, 2000).

Other researchers have used brain scans, including positron emission tomography (PET) scans, to learn how people process and retain information. From these studies, it seems the prefrontal cortex is involved. In one study, participants had to complete two different tasks: either looking for the letter a in words (considered a perceptual task) or categorizing a noun as either living or non-living (considered a semantic task) (Kapur et al., 1994). Participants were then asked which words they had previously seen. Recall was much better for the semantic task than for the perceptual task. According to PET scans, there was much more activation in the left inferior prefrontal cortex in the semantic task. In another study, encoding was associated with left frontal activity, while retrieval of information was associated with the right frontal region (Craik et al., 1999).

Neurotransmitters

There also appear to be specific neurotransmitters involved with the process of memory, such as epinephrine, dopamine, serotonin, glutamate, and acetylcholine (Myhrer, 2003). There continues to be discussion and debate among researchers as to which neurotransmitter plays which specific role (Blockland, 1996). Although we don’t yet know which role each neurotransmitter plays in memory, we do know that communication among neurons via neurotransmitters is critical for developing new memories. Repeated activity by neurons leads to increased neurotransmitters in the synapses and more efficient and more synaptic connections. This is how memory consolidation occurs.

It is also believed that strong emotions trigger the formation of strong memories, and weaker emotional experiences form weaker memories; this is called arousal theory (Christianson, 1992). For example, strong emotional experiences can trigger the release of neurotransmitters, as well as hormones, which strengthen memory; therefore, our memory for an emotional event is usually better than our memory for a non-emotional event. When humans and animals are stressed, the brain secretes more of the neurotransmitter glutamate, which helps them remember the stressful event (McGaugh, 2003). This is clearly evidenced by what is known as the flashbulb memory phenomenon.

Learn more about flashbulb memories in this brief video.

You can view the transcript for “Flashbulb Memories” here (opens in new window) .

A flashbulb memory is an exceptionally clear recollection of an important event (Figure 2). Where were you when you first heard about the 9/11 terrorist attacks? Most likely you can remember where you were and what you were doing. In fact, a Pew Research Center (2011) survey found that for those Americans who were age 8 or older at the time of the event, 97% can recall the moment they learned of this event, even a decade after it happened.

Dig Deeper: Inaccurate and False Memories

I was sitting there, and my Chief of Staff—well, first of all, when we walked into the classroom, I had seen this plane fly into the first building. There was a TV set on. And you know, I thought it was pilot error and I was amazed that anybody could make such a terrible mistake. (Greenberg, 2004, p. 2)

Contrary to what President Bush recalled, no one saw the first plane hit, except people on the ground near the twin towers. The plane hitting the first tower was not initially broadcasted on television because it had been a normal Tuesday morning in New York City until the first plane hit.

Some people attributed Bush’s wrong recall of the event to conspiracy theories. However, there is a much more benign explanation: human memory, even flashbulb memories, can be frail. In fact, memory can be so frail that we can convince a person an event happened to them, even when it did not. In studies, research participants will recall hearing a word, even though they never heard the word. For example, participants were given a list of 15 sleep-related words, but the word “sleep” was not on the list. Participants recalled hearing the word “sleep” even though they did not actually hear it (Roediger & McDermott, 2000). The researchers who discovered this named the theory after themselves and a fellow researcher, calling it the Deese-Roediger-McDermott paradigm.

Think It Over

Describe a flashbulb memory of a significant event in your life.

CC licensed content, Original

• Flashbulb Memory. Authored by : Kara McCord. Located at : https://youtu.be/mPhW9bUI4F0 . License : Other . License Terms : Standard YouTube License
• Modification, adaptation, and original content. Provided by : Lumen Learning. License : CC BY: Attribution

CC licensed content, Shared previously

• Parts of the Brain Involved with Memory. Authored by : OpenStax College. Located at : https://openstax.org/books/psychology-2e/pages/8-2-parts-of-the-brain-involved-with-memory . License : CC BY: Attribution . License Terms : Download for free at https://openstax.org/books/psychology-2e/pages/1-introduction

physical trace of memory

some parts of the brain can take over for damaged parts in forming and storing memories

strong emotions trigger the formation of strong memories and weaker emotional experiences form weaker memories

exceptionally clear recollection of an important event

General Psychology Copyright © by OpenStax and Lumen Learning is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

Share This Book

Psychologically speaking: your brain on writing

Remember when you were little and just learning how to write? Just writing your name was a huge accomplishment. Yet with practice, it became much easier. The brain is not a muscle; although, in some ways it develops like one. The more you use it in a specific way, the more able it is to perform the task. So what is the brain actually doing while you write? The following are a number of brain areas that work together to form ideas and get them down on paper.

Frontal Lobe

Hippocampus

Broca’s Area

Wernicke’s Area

Visual Cortex vs Speech Area

Caudate Nucleus

• communication ,
• nonfiction ,
• psychology ,
• writing process ,
• Current students ,
• Current undergraduate students ,
• Current graduate students

Home — Essay Samples — Nursing & Health — Human Brain — Anatomy of the Brain

Anatomy of The Brain

• Categories: Human Brain

About this sample

Words: 586 |

Published: Jan 4, 2019

Words: 586 | Page: 1 | 3 min read

Cite this Essay

Let us write you an essay from scratch

• 450+ experts on 30 subjects ready to help
• Custom essay delivered in as few as 3 hours

Get high-quality help

Dr. Karlyna PhD

Verified writer

• Expert in: Nursing & Health

+ 120 experts online

By clicking “Check Writers’ Offers”, you agree to our terms of service and privacy policy . We’ll occasionally send you promo and account related email

No need to pay just yet!

Related Essays

4 pages / 1884 words

3 pages / 1416 words

2 pages / 1119 words

2 pages / 1178 words

Remember! This is just a sample.

You can get your custom paper by one of our expert writers.

121 writers online

Still can’t find what you need?

Browse our vast selection of original essay samples, each expertly formatted and styled

Related Essays on Human Brain

My impression of Dennett’s location throughout the story is that he is where he is told. When the experiment started, he was supposed to be in Houston, then he was sent to Tulsa for the radioactive device, and at last he [...]

Amyotrophic lateral sclerosis also known as ALS or Lou Gehrig’s disease is a disease. This disease attacks nerve cell and pathways to the brain and the spain cord. The nerve cells that are being attacked control muscle function [...]

Working memory is a part of the human memory system with a limited capacity. Working Memory’s job is holding temporarily information for processing. Working memory refers to information storage without manipulation. About [...]

“Memory is the diary we all carry about with us,” Oscar Wilde once said. Now for a second imagine a life without any memories! One wouldn’t be able to remember his/her name, how to look after themselves or to even recognize [...]

Addiction has an enormous impact on the people lives especially in the manner in which it affects their lives. Furthermore, this also affects their families since it has the tendencies of putting the relationships at risks due [...]

Two or three meningeal sinuses may join to form a vestibule just before reaching the superior sagittal sinus. There is a tendency for the veins draining the lateral surface of the anterior frontal and posterior parietal regions [...]

Related Topics

By clicking “Send”, you agree to our Terms of service and Privacy statement . We will occasionally send you account related emails.

Where do you want us to send this sample?

By clicking “Continue”, you agree to our terms of service and privacy policy.

Be careful. This essay is not unique

This essay was donated by a student and is likely to have been used and submitted before

Download this Sample

Free samples may contain mistakes and not unique parts

Sorry, we could not paraphrase this essay. Our professional writers can rewrite it and get you a unique paper.

Please check your inbox.

We can write you a custom essay that will follow your exact instructions and meet the deadlines. Let's fix your grades together!

Get Your Personalized Essay in 3 Hours or Less!

We use cookies to personalyze your web-site experience. By continuing we’ll assume you board with our cookie policy .

• Instructions Followed To The Letter
• Deadlines Met At Every Stage
• Unique And Plagiarism Free

• - Google Chrome

Intended for healthcare professionals

• Access provided by Google Indexer
• My email alerts
• BMA member login
• Username * Password * Forgot your log in details? Need to activate BMA Member Log In Log in via OpenAthens Log in via your institution

Search form

• Advanced search
• Search responses
• Search blogs
• News & Views
• What is brain health...

What is brain health and why is it important?

Read our brain health collection.

• Related content
• Peer review
• Yongjun Wang , professor 1 2 ,
• Yuesong Pan , associate professor 1 2 ,
• Hao Li , professor 1 2
• 1 Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
• 2 China National Clinical Research Center for Neurological Diseases, Beijing, China
• Correspondence to: Y Wang yongjunwang{at}ncrcnd.org.cn

Yongjun Wang and colleagues discuss the definition of brain health and the opportunities and challenges of future research

The human brain is the command centre for the nervous system and enables thoughts, memory, movement, and emotions by a complex function that is the highest product of biological evolution. Maintaining a healthy brain during one’s life is the uppermost goal in pursuing health and longevity. As the population ages, the burden of neurological disorders and challenges for the preservation of brain health increase. It is therefore vital to understand what brain health is and why it is important. This article is the first in a series that aims to define brain health, analyse the effect of major neurological disorders on brain health, and discuss how these disorders might be treated and prevented.

Definition of brain health

Currently, there is no universally recognised definition of brain health. Most existing definitions have only a general description of normal brain function or emphasise one or two dimensions of brain health. The US Centers for Disease Control and Prevention defined brain health as an ability to perform all the mental processes of cognition, including the ability to learn and judge, use language, and remember. 1 The American Heart Association/American Stroke Association (AHA/ASA) presidential advisory defined optimal brain health as “average performance levels among all people at that age who are free of known brain or other organ system diseases in terms of decline from function levels, or as adequacy to perform all activities that the individual wishes to undertake.” 2

The brain is a complex organ and has at least three levels of functions that affect all aspects of our daily lives: interpretation of senses and control of movement; maintenance of cognitive, mental, and emotional processes; and maintenance of normal behaviour and social cognition. Brain health may therefore be defined as the preservation of optimal brain integrity and mental and cognitive function at a given age in the absence of overt brain diseases that affect normal brain function.

Effect of major neurological disorders on brain health

Several neurological disorders may disrupt brain function and affect humans’ health. Medically, neurological disorders that cause brain dysfunction can be classified into three groups:

Brain diseases with overt damage to brain structures, such as cerebrovascular diseases, traumatic brain injury, brain tumours, meningitis, and communication and sensory disorders

Functional brain disorders with detectable destruction of brain connections or networks, such as neurodegenerative diseases (eg, Parkinson’s disease, Alzheimer’s disease, and other dementias) and mental disorders (eg, schizophrenia, depression, bipolar disorder, alcoholism, and drug abuse)

Other brain disorders without detectable structural or functional impairment, such as migraine and sleep disorders.

These neurological disorders may have different or common effects on brain health and function. For instance, Alzheimer’s disease is the main type of dementia, with a decline in different domains of cognitive function. Mood disorders may cause dysfunction in execution, reward processing, and emotional regulations. In addition to physical disability, aphasia, gait and balance problems, and cerebrovascular diseases may lead to cognitive impairment and dementia, which are neglected by both patients and physicians.

Ageing and burden of neurological disorders

Human ageing is mainly reflected in the aspects of brain ageing and degradation of brain function. The number of people aged 60 years and over worldwide was around 900 million in 2015 and is expected to grow to two billion by 2050. 3 With the increases in population ageing and growth, the burden of neurological disorders and challenges to the preservation of brain health steeply increase. People with neurological disorders will have physical disability, cognitive or mental disorders, and social dysfunction and be a large economic burden.

Globally, neurological disorders were the leading cause of disability adjusted life years (276 million) and the second leading cause of death (9 million) in 2016, according to the Global Burden of Diseases study. 4 Stroke, migraine, Alzheimer’s disease and other dementias, and meningitis are the largest contributors to neurological disability adjusted life years. 4 About one in four adults will have a stroke in their lifetime, from the age of 25 years onwards. 5 Roughly 50 million people worldwide were living with dementia in 2018, and the number will more than triple to 152 million by 2050. 6 In the following decades, governments will face increasing demand for treatment, rehabilitation, and support services for neurological disorders.

Opportunities and challenges of future research on brain health

Opportunities and challenges exist in the assessment of brain health, the mechanism of brain function and dysfunction, and approaches to promote brain health ( box 1 ).

Lack of metrics or tools to comprehensively assess or quantify brain health

Little knowledge about the mechanisms of brain function and dysfunction

Few effective approaches to prevent and treat brain dysfunction in some major neurological disorders, such as dementia

Need to precisely preserve brain functions for people with neurosurgical diseases

Defining and promoting optimal brain health require the scientific evaluation of brain health. However, it is difficult to comprehensively evaluate or quantify brain health through one metric owing to the multidimensional aspects of brain health. Many structured or semistructured questionnaires have been developed to test brain health by self-assessments or close family member assessments of daily function or abilities. In recent decades new structural and functional neuroimaging techniques have been applied to evaluate brain network integrity and functional connectivity. 7 However, these subjective or objective measures have both strengths and weaknesses. For instance, scales such as the mini-mental state examination and Montreal cognitive assessment are simple and easy to implement but are used only as global screening tools for cognitive impairment; tests such as the digit span, Rey-Osterrieth complex figure test, trail making A and B, Stroop task, verbal fluency test, Boston naming test, and clock drawing test are used mainly to assess one or two specific domains of memory, language, visuospatial, attention, and executive function; and neuroimaging techniques, although non-invasive and objective, still have disadvantages of test contraindications, insufficient temporal or spatial resolution, motion artefact, and high false discovery rates, which limit their clinical transformation.

Another difficulty in measuring brain health is that age, culture, ethnicity, and geography specific variations exist in the perception of optimal brain health. Patient centred assessment of brain function, such as self-perception of cognitive function and quality of life, should also be considered when measuring brain health. 8 Universal acceptable, age appropriate, multidimensional, multidisciplinary, and sensitive metrics or tools are required to comprehensively measure and monitor brain function and brain health.

To promote optimal brain health, we need a better understanding of the mechanisms of brain function and dysfunction. Unfortunately, little is known about the working mechanism of the brain. Although we have made considerable developments in neuroscience in recent decades, we still cannot totally decipher the relations between spatiotemporal patterns of activity across the interconnected networks of neurons and thoughts or the cognitive and mental state of a person. 9 Recent progress in brain simulation and artificial intelligence provides a vital tool to understand biological brains, and vice versa. 10 11 The development of brain inspired computation, brain simulation, and intelligent machines was emphasised in the European Union and China Brain Project. 9 12

Meanwhile, the mechanisms behind the brain dysfunction in some neurological disorders are still not well understood, especially for mental and neurodegenerative disorders. Further investigation of the mechanisms of brain diseases may indicate approaches to treatment and improve brain function. Brain imaging based cognitive neuroscience may unravel the underlying brain mechanism of cognitive dysfunction and provide an avenue to develop a biological framework for precision biomarkers of mood disorders. 13

Most common neurological diseases, such as cerebrovascular diseases and Alzheimer’s disease, have complex aetiopathologies, typically involving spatial-temporal interactions of genetic and environmental factors. However, a single genetic factor could account for the disease progression of monogenic neurological disorders. These diseases could be more readily investigated by simplified cross species modelling, leading to better understanding of their mechanisms and greater efficiency in testing innovative therapies. Such research may provide a window to promote the investigation of common neurological disorders and general brain health, as discussed by Chen and colleagues elsewhere in this series. 14

Few effective approaches are available to prevent and treat brain dysfunction in some major neurological disorders, such as dementia. Neurons are not renewable, and brain dysfunction is always irreversible. Recent trials targeting amyloid clearance and the selective inhibition of tau protein aggregation failed to improve cognition or modify disease progression in patients with mild Alzheimer’s disease. 15 16 More attention has focused on other potential therapeutic targets, such as vascular dysfunction, inflammation, and the gut microbiome, as discussed by Shi and colleagues. 17 In particular, recent studies showed that the early impairment of cognition was induced by the disruption of neurovascular unit integrity, which may cause hypoperfusion and the breakdown of the blood-brain barrier and subsequent impairment in the clearance of proteins in the brain. 18 19 Physical activity, mental exercise, a healthy diet and nutrition, social interaction, ample sleep and relaxation, and control of vascular risk factors are considered six pillars of brain health. The AHA/ASA presidential advisory recommended the AHA’s Life’s Simple 7 (non-smoking, physical activity, healthy diet, appropriate body mass index, blood pressure, total cholesterol, and blood glucose) to maintain optimal brain health. 2 Pan and colleagues discuss how this may indicate a new dawn of preventing some cognitive impairment and brain dysfunction by preventing vascular risk factors or cerebrovascular diseases. 20

For other neurological disorders with potential therapeutic approaches, the main aim is to preserve brain function. Impaired brain function due to anatomical structural damage is underestimated in patients with neurosurgical diseases such as brain tumours, trauma, and epilepsy. In recent years, treatment targets for neurosurgical diseases have changed from focusing on survival or life expectancy to balancing brain structures and functions. Precise preservation of brain function requires an understanding of the exquisite relation between brain structure and function and advanced technologies to visualise brain structure-function relations. 21

Another example of the predicament associated with protection of brain function is uncertainty in the treatment response in epilepsy management. Current standard care for epilepsy relies on a trial and error approach of sequential regimens of antiseizure medications. The time delay due to this treatment approach means that such treatments may be less effective and irreversible damage may occur. Chen and colleagues 22 describe how recent advances in personalised epilepsy management based on artificial intelligence, genomics, and patient derived stem cells are bringing some hope to overcome this predicament in epilepsy management and promise a more effective strategy. 23 24

Brain health is the maintenance of multidimensional aspects of brain function. However, several neurological disorders may affect brain health in one or more aspects of brain function. Deciphering and promoting the function and health of the brain, the most mysterious organ in the human body, will have a dramatic impact on science, medicine, and society. 25 In the past seven years, a number of large scale brain health initiatives have been launched in several countries to promote the development of neuroscience, brain simulation, and brain protection. 9 However, further challenges are raised by the different key research directions of brain projects in different countries. In the face of these challenges, Liu and colleagues argue that collaboration on brain health research is urgently needed. 26 As the other articles in this series describe, coordinated research has enormous potential to improve the prognosis of brain disorders.

Key messages

Brain health is the preservation of optimal brain integrity and mental and cognitive function and the absence of overt neurological disorders

Human ageing increases the burden of brain dysfunction and neurological diseases and the demands for medical resources

Further studies are required to assess brain health, understand the mechanism of brain function and dysfunction, and explore effective approaches to promote brain health.

Contributors and sources: YW proposed the idea for this series on brain health. YW and YP drafted the first manuscript. All the authors critically reviewed and revised the manuscript. YP and HL expertise is in the area of clinical research methods and clinical research on stroke. YW is an expert in clinical research on stroke and neurological diseases. YW is the guarantor.

Competing interests We have read and understood BMJ policy on declaration of interests and declare that the study was supported by grants from the National Science and Technology Major Project (2017ZX09304018), National Key R&D Program of China (2018YFC1312903, 2017YFC1310902, 2018YFC1311700, and 2018YFC1311706), National Natural Science Foundation of China (81971091), Beijing Hospitals Authority Youth Programme (QML20190501), and Beijing Municipal Science and Technology Commission (D171100003017002).

Provenance and peer review: Commissioned; externally peer reviewed.

This article is part of a series launched at the Chinese Stroke Association annual conference on 10 October 2020, Beijing, China. Open access fees were funded by the National Science and Technology Major Project. The BMJ peer reviewed, edited, and made the decision to publish these articles.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/ .

• ↵ Centers for Disease Control and Prevention. Healthy aging. What is a healthy brain? New research explores perceptions of cognitive health among diverse older adults. https://www.cdc.gov/aging/pdf/perceptions_of_cog_hlth_factsheet.pdf
• Gorelick PB ,
• Iadecola C ,
• American Heart Association/American Stroke Association
• ↵ WHO Global Health Ethics team. Ageing. https://www.who.int/ethics/topics/ageing/en/ . 2019
• GBD 2016 Neurology Collaborators.
• Feigin VL ,
• GBD 2016 Lifetime Risk of Stroke Collaborators
• ↵ Alzheimer’s Disease International. World Alzheimer report 2018. The state of the art of dementia research: new frontiers. https://www.alz.co.uk/research/world-report-2018
• Gordon MF ,
• Lenderking WR ,
• Patient-Reported Outcome Consortium’s Cognition Working Group
• Ullman TD ,
• Tenenbaum JB ,
• Gershman SJ
• Hassabis D ,
• Kumaran D ,
• Summerfield C ,
• Botvinick M
• Capitão L ,
• Satterthwaite TD ,
• Thomas RG ,
• Alzheimer’s Disease Cooperative Study Steering Committee ,
• Solanezumab Study Group
• Gauthier S ,
• Feldman HH ,
• Schneider LS ,
• Sabbagh MN ,
• Henstridge CM ,
• Spires-Jones TL
• Sweeney MD ,
• Montagne A ,
• Zlokovic BV
• Wardlaw JM ,
• Couldwell WT ,
• Antonic-Baker A ,
• Kuhlmann L ,
• Lehnertz K ,
• Richardson MP ,
• Schelter B ,
• Epi4K Consortium
• Schwamm LH ,
• Koroshetz WJ