The Brain & How It Talks To the Body

The Brain & How It Talks
To the Body

We all know we have a brain. We know what a brain looks like. We know that we think. We know that our brain controls our movements. We know that is words because we're breathing and our heart is beating... although we wonder sometimes how well it works, especially on those occasions when we go into the kitchen and forget why we went in there. Or look for something that ends up being right in front of my face (am we alone here?). What goes wrong in these instances?

Sure, we learned about the brain in school. But if you’re like us, that was more than a few years ago. What do you remember about the brain and how it works? How does it communicate with the body? Here is a brief rundown if you need a refresher, as we did. It is a lot of information, but we have tried to simplify it to make it easy to understand and piece together. Particular attention is paid to areas that research has shown measurable differences in FND patients (see the Research page).

Overview of the Brain

Note: Although the brain is broken down into different sections/areas, it is important to remember that the brain is a constant interaction of these various sections. No one area works by itself- every thought or action is always a result of a 'group effort' or these areas.

Fun fact: Did you know? The brain is about 60% fat. The remaining 40% is a combination of water, protein, carbs, and salts. The brain itself isn’t a muscle; it contains blood vessels and nerves, including neurons and glial cells.

The forebrain consists primarily of the cerebrum and structures underneath it (the ‘inner brain’). It is the largest part of the brain, as well as the most highly developed part of the brain.

The cerebrum, which sits at the topmost part of the brain, is where our conscious thoughts and actions come from. It holds memories, and allows you to plan, think, and use your imagination. It is split into two halves (called hemispheres), by a groove called ‘the great longitudinal fissure’. The two hemispheres look the same in appearance, but they have different functions. For example, the ability to form words lies primarily in the left hemisphere, while the right hemisphere controls many abstract reasoning skills. Interestingly, each hemisphere controls the opposite side of the body - the right cerebral hemisphere primarily controls the left side of the body, and the left hemisphere primarily controls the right side. The two cerebral hemispheres communicate through the corpus callosum, which joins the two hemispheres at the bottom.

The corpus callosum, is a thick, C-shaped, tract of nerve fibers that lies at the base of the deep fissure that splits the two hemispheres of the cerebrum.

Each cerebral hemisphere can be further divided into sections that specialize in different functions.

The frontal lobes lie directly behind the forehead. It is involved in personality characteristics, decision-making, speech, voluntary movement, and behavioral functions. When you plan a schedule, imagine the future, or use reasoned arguments, these two lobes do much of the work. One of the ways the frontal lobes seem to do these things is by acting as short-term storage sites, allowing one idea to be kept in mind while considering other ideas.

The motor cortices help plan, control, and execute voluntary movement, like wiggling your fingers or throwing a ball. The premotor cortex, found beside the primary motor cortex, guides eye and head movements, as well as a person’s sense of orientation.

The parietal lobes lie behind the frontal lobes. When you enjoy a good meal—the taste, smell, and texture of the food— the parietal lobes are at work. They interpret signals received from other areas of the brain simultaneously. They also support reading and arithmetic. A person’s memory, and the new information received, give meaning to objects.

The somatosensory cortices areas receive information from the rest of the body about temperature, taste, touch, and movement.

The occipital lobes process images from the eyes and link that information with images stored in memory, and influence how we process colors and shapes.

The temporal lobes lie under the parietal and frontal lobes, about ear level. At the top of each temporal lobe is an area responsible for receiving information from the ears. The underside of each temporal lobe plays a crucial role in forming and retrieving memories. Other parts of this lobe integrate memories and sensations of taste, sound, sight, and touch.

The midbrain, or mesencephalon, is the uppermost part of the brainstem. It controls some reflex actions, and is part of the circuit involved in controlling eye movements and other voluntary movements. It is a very complex structure with a range of different neuron clusters, neural pathways and other structures. These features facilitate various functions, from hearing and movement to calculating responses and environmental changes.

The hindbrain includes the upper part of the spinal cord, the brainstem, and the cerebellum. It controls the body’s vital, automatic, functions, such as respiration and heart rate.

The cerebellum is a wrinkled ball of tissue, and is located at the back of the brain beneath the occipital lobes. It is separated from the cerebrum by the tentorium (a fold of dura, or tissue in the brain). It fine tunes motor activity and movements, helps maintain posture, and helps our sense of balance or equilibrium.

The brainstem is the lower extension of the brain, located in front of the cerebellum and connected to the spinal cord. It serves as a relay station, passing messages back and forth between various parts of the body and the cerebral cortex. The structure consists of the brainstem, pons and medulla oblongata. Originating in the brainstem are 10 of the 12 cranial nerves.

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. It produces reflexive activities such as sneezing, vomiting, coughing and swallowing.

Named for the Latin word for “bridge,” the pons is the connection between the midbrain and the medulla, and is the origin for four of the 12 cranial nerves.

The cerebral cortex is a layer of tissue, about 2-3 dimes thick, that coats the surface of both the cerebrum and cerebellum, made up of billions of neurons and glia. This is where most of the actual information processing takes place and is called the ‘gray matter’. The cerebral cortex has small grooves (called sulci), larger grooves (called fissures), and bulges between the grooves (called gyri), which make the surface of the brain appear wrinkled. The folds add to its surface area and therefore increase the amount of gray matter, and the volume of information that can be processed. Beneath the cerebral cortex, connecting fibers between neurons form a white-colored area called ‘white matter’.

Cerebral Cortex

Temporoparietal Junction (TPJ)

The temporoparietal junction (TPJ) is a heteromodal association cortex (meaning an area that receives input from multiple other areas) that is located, in each hemisphere, at the intersection of the parietal and the temporal lobe. It integrates inputs from the the limbic system, as well as from visual, auditory and somatosensory areas, and is reciprocally connected with prefrontal and temporal cortices, which enables it to process information from the external environment as well as from the internal environment.

The TPJs' functions are mainly associated with attention and social cognition. Its anterior (front) and posterior (back) parts have distinct connectivity and functional profiles, suggesting that they deal with different high-level processes contributing to monitoring for salient stimuli (something that catches our attention) and reasoning about oneself and others, respectively.

The 'Inner Brain'

The 'inner brain' includes the structures that lie under the cerebrum in the forebrain.

The hypothalamus, about the size of a pearl, is located above the pituitary gland, and sends chemical messages that control its function. It wakes you up in the morning and gets your adrenaline flowing when needed. It regulates body temperature, controls hunger and thirst, and plays a role in some aspects of memory. It is also an important emotional center, controlling the chemicals that make you feel exhilarated, angry, or unhappy.

The thalamus, near the hypothalamus, serves as a relay station for almost all information that comes and goes to the cortex. It is located at the center of the limbic system and is a meeting point of many neural pathways. It plays a role in pain sensation, attention and alertness. The thalamus consists of four parts: the hypothalamus, the epithalamus, the ventral thalamus and the dorsal thalamus.

The basal ganglia are clusters of nerve cells that surround the thalamus. They are responsible for initiating and integrating movements. They are also involved in reward processing and habit formation.

The amygdala are almond-shaped structures located under each hemisphere of the brain, right next to the hippocampus. They are a part of the limbic system, and regulate emotion and memory. They also attach emotional content to our memories, and therefore play a role in determining how those memories are stored. They are also associated with the brain’s reward system, stress, and the “fight or flight” response when someone perceives a threat. Researchers have recently confirmed that new neurons are made here (see neuroplasticity).

The hippocampus is an arching, seahorse-shaped, tract of nerve cells on the underside of each temporal lobe that lead from the hypothalamus to the thalamus. It is part of a larger structure called the hippocampal formation. It is essentially the memory center of our brains, sending memories out to the appropriate area for long-term storage and retrieving when necessary, which in return supports learning and navigation. It is also important for our spatial orientation and our ability to navigate the world. The hippocampus is one site in the brain where new neurons are made from adult stem cells (see neuroplasticity).

The pineal gland, shaped like a tiny pinecone, is located deep in the brain and is attached by a stalk to the top of the third ventricle. Its main job is to help control the circadian cycle (our cycle of sleep and wakefulness) by secreting melatonin (a hormone). The pineal gland is part of the endocrine system, was the last part to be discovered, and is the least understood gland of the endocrine system.

The pituitary gland, about the size of a pea, is attached to an area at the base of the brain (behind the nose) called the pituitary fossa or sella turcica. It is often called the ‘master gland’ because it controls the secretion of hormones. It is responsible for controlling and coordinating growth and development, various body organ function (i.e. kidney, breasts, uterus), and the function of other glands (i.e. thyroid, gonads, adrenal glands). It receives chemical signals from the hypothalamus through its stalk and blood supply.

The posterior fossa is a cavity in the back part of the skull which contains the cerebellum, brainstem, and cranial nerves 5-12.

Cranial Nerves

Inside the cranium (skull), there are 12 nerves. The first two nerves originate in the cerebrum, and the remaining 10 cranial nerves emerge from the brainstem.

1: The first is the olfactory nerve, which allows for your sense of smell.

2: The optic nerve governs eyesight.

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.

4: The trochlear nerve controls muscles in the eye. It emerges from the back of the midbrain part of the brainstem.

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 more.

6: The abducens nerve innervates some of the muscles in the eye.

7: The facial nerve supports face movement, taste, glandular and other functions.

8: The vestibulocochlear nerve facilitates balance and hearing.

9: The glossopharyngeal nerve allows taste, ear and throat movement, and has many more functions.

10: The vagus nerve allows sensation around the ear and the digestive system and controls motor activity in the heart, throat and digestive system.

11: The accessory nerve innervates specific muscles in the head, neck and shoulder.

12: The hypoglossal nerve supplies motor activity to the tongue.

The Vagus Nerve

“Vagus” is the Latin word for wandering. Your vagal nerves take a long, winding course through your body, exiting from your medulla oblongata in your lower brainstem, passing through your neck, chest, heart, lungs, abdomen, and digestive tract. The vagus nerves are the main nerves of your parasympathetic nervous system and contain 75% of your parasympathetic nerve fibers (see body systems).

Your left and right vagal nerves join to form the vagal trunk. They connect at your esophageal hiatus, the opening where your esophagus passes into your abdominal cavity (stomach). The vagal trunk includes anterior (front) and posterior (back) gastric nerves that go to your abdomen.

You have three vagal nerve branches: the inferior ganglion branch, superior ganglion branch, and vagus nerve branch.

The vagus nerve has two sensory ganglia (masses of nerve tissue that transmit sensory impulses): the superior and the inferior ganglia. The branches of the superior ganglion stimulate the skin in the concha of the ear. The inferior ganglion gives off two branches: the pharyngeal nerve and the superior laryngeal nerve. The recurrent laryngeal nerve branches from the vagus in the lower neck and upper chest activate the muscles of the larynx (voice box). The vagus also gives off cardiac, esophageal, and pulmonary (lung) branches. In the abdomen the vagus activates the greater part of the digestive tract. Its pharyngeal and laryngeal branches transmit motor impulses to the pharynx (throat) and larynx (voice box); its cardiac branches act to slow the rate of heartbeat; its bronchial branch acts to constrict the bronchi; and its esophageal branches control involuntary muscles in the esophagus, stomach, gallbladder, pancreas, and small intestine, stimulating peristalsis and gastrointestinal secretions.

The Body's Systems

These are the main systems that keep our bodies functioning:

The endocrine system controls hormone production.
The respiratory system exchanges gas between the internal and external environment.
The digestive system allows absorption of nutrients through the physical and chemical breakdown of food.
The reproductive system produces reproductive cells that will generate offspring.
The integumentary system protects against the external environment and regulation of temperature.
The muscular system controls voluntary and involuntary movement.
The skeletal system supports and protects our internal organs.
The urinary system filtrates our blood and excretes waste from the body.
The lymphatic system controls circulation of lymph, which maintains fluid balance and helps fight infection.
The cardiovascular system controls circulation of blood, which transports gases, nutrients, hormones, and wastes.

The Limbic System

The limbic system is the part of the brain involved in our behavioral and emotional responses, especially when it comes to behaviors needed for survival. This system also governs our motivation, our sense of smell, and is involved in the formation of long-term memory. Because of the complex interconnectedness with different parts of the brain, there is some disagreement on the components of the limbic system, however, the primary components typically included by researchers include the thalamus, hypothalamus, basal ganglia, cingulate gyrus, hippocampus, and amygdala.

The Nervous System

The nervous system consists of two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). Your brain and spinal cord make up your CNS. Your brain reads the signals from your nerves to regulate how you think, move and feel. The PNS is made up of the network of nerves that branch out from your spinal cord. It relays information from the CNS to the rest of your body. The PNS is comprised of two parts: the somatic nervous system (SNS), which guides your voluntary movements, and the autonomic nervous system (ANS), which regulates involuntary and automatic movements.

The nervous system is made up of the brain, spinal cord and nerves. It is composed of neurons and glial cells that function together to create complex behaviors. There are several different types of both glia and neurons, each with specific functions. Glia function mainly to modulate neuron function and signaling. Glia perform many diverse functions including making myelin; modulating synapse formation, function, and elimination; regulating blood flow and metabolism; and maintaining ionic and water homeostasis. It uses neurons to generate and propagate electrical and chemical signals that travel among your brain, skin, organs, glands, and muscles. The messages help you move your limbs and feel sensations.

To sum it all up: Your eyes, ears, tongue, nose and the nerves all over your body are constantly taking in information about your environment. Your nerves carry that data to and from your brain. Imagine your nervous system as a tree. Your central nervous system is the trunk of the tree that contains your brain and spinal cord. The tree branches are your peripheral nervous system (nerves). The branches extend from the truck (brain and spinal cord) to reach all parts of your body. The nervous system keeps track of what’s going on inside and outside of your body and decides how to respond to any situation you’re in.

Enteric Nervous System (ENS) & Gut-Brain Axis (GBA)

The gut-brain axis is the network of nerves that connect your brain and stomach and send signals back and forth. But your nervous system also works closely with your endocrine system, which produces hormones that communicate things like hunger, fullness and stress. And it works closely with your immune system to respond appropriately to injury or disease in your gut. The enteric nervous system (ENS) is a part of the gut-brain axis (GBA). You may have heard the saying that the gut/stomach is your second brain. This is what sends the signals when we experience 'butterflies' in our stomach when we're nervous or 'go with our gut' to make a decision.

The ENS is two thin layers of more than 100 million nerve cells lining your gastrointestinal tract from esophagus to rectum. It is the most complex neural network outside of your brain, and is unique in that it can operate somewhat independently from your brain and central nervous system (C NS), hence the 'second brain' reference. It is a special division of your ANS and works as a part of your overall ANS, but also on its own. It can gather information about the conditions inside your GI tract, process that information locally and generate a response without sending it back to your brain. Its main role is controlling digestion, from swallowing to the release of enzymes that break down food to the control of blood flow that helps with nutrient absorption to elimination. The vagus nerve is a key connection in this system.

Neurons & Glia Cells

The brain and the rest of the nervous system are composed of many different types of cells, but the primary units are neurons and glia cells. Neurons are information messengers. They use electrical and chemical signals to send information between diﬀerent areas of the brain, as well as between the brain and the entire body. All sensations, movements, thoughts, memories, and feelings are the result of neurons and their support cells, the glial cells.

Neurons consist of 3 parts:
- The cell body (soma): contains the nucleus, where most of the molecules that the neuron needs to survive and function are manufactured
- Dendrites: extend out from the cell body like the branches of a tree and receive messages from other nerve cells; they are usually, but not always, short and branching, which increases their surface area to receive signals from other neurons. The number of dendrites on a neuron varies, and they are called afferent processes because they transmit impulses to the neuron cell body. In addition to afferent signaling, dendrites can be involved in protein synthesis and independent signaling functions with other neurons.
- Axon: some may be very short, such as those that carry signals from one cell in the cortex to another cell less than a hair’s width away; others may be very long, such as those that carry messages from the brain all the way down the spinal cord. Axons typically end in an axon terminal at which neurotransmitters, neuromodulators, or neurohormones are released in the conversion of the electrical signal to a chemical signal which can cross the synapse or neuromuscular junction. Because it carries impulses away from the cell body, it is called an efferent process.

There are 3 types of neurons. Within these 3 kinds of neurons are hundreds of different types, each able to send and receive messages in different ways. How these neurons communicate with each other by making connections is what makes each of us unique in how we think, feel, and act.

Sensory neurons: activated by sensory input from the environment; inputs can be physical or chemical (i.e. a physical input can be things like sound, touch, heat, or light; a chemical input comes from taste or smell, which neurons then send to the brain). Most sensory neurons are pseudounipolar (they only have one axon which is split into two branches)
Motor neurons: connect to muscles, glands and organs throughout the body. Motor neurons have the most common type of ‘body plan’ for a nerve cell - they are multipolar (have one axon and several dendrites). There are two types of motor neurons: lower motor neurons (those that travel from spinal cord to muscle) and upper motor neurons (those that travel between the brain and spinal cord)
Interneurons: connect motor and sensory neurons. As well as transferring signals between sensory and motor neurons, they can also communicate with each other, forming circuits of various complexity. They are also multipolar (have one axon and several dendrites).

Glia Cells

Glia cells are also called 'neuroglia', which means 'nerve glue'. Neurons and glial cells function together in the nervous system to create complex behaviors. As we have learned, neurons generate and propagate electrical and chemical signals. Glia cells, on the other hand, function mainly to modulate neuron function and signaling. Specifically glia cells perform many functions including making myelin; modulating synapse formation, function, and elimination; regulating blood flow and metabolism; and maintaining ionic and water homeostasis. As with neurons, there are many different types of glia cells, each specialized for a particular function. Some are specific to the central nervous system (CNS), whereas others are found only in the peripheral nervous system (PNS).

Microglia are the brain’s immune cells, serving to protect it against injury and disease. They identify when something has gone wrong and initiate a response that removes the toxic agent and/or clears away the dead cells. Thus they are the brain’s protectors.

Macroglia:

Astrocytes are star-shaped cells that maintain a neuron’s working environment. They do this by controlling the levels of neurotransmitter around synapses, controlling the concentrations of important ions like potassium, and providing metabolic support. But they don’t just maintain the environment around synapses. An active area of research addresses how they modulate how neurons communicate. Because they have the ability to sense neurotransmitter levels in synapses, and can respond by releasing molecules that directly influence neuronal activity, astrocytes are increasingly seen as important for modifying synapses.
Oligodendrocytes provide support to axons of neurons in the central nervous system, particularly those that travel long distances within the brain. They produce a fatty substance called myelin, which is wrapped around axons as a layer of insulation. Similar in function to insulation layers around power cables, the myelin sheath allows electrical messages to travel faster, and gives white matter its name—the white is the myelin wrapped around axons.

Other glia cell types:

In CNS:
- Ependymal cells: line the spinal cord and ventricles of the brain. They are involved in creating cerebrospinal fluid (CSF).
- Radial glia: progenitor cells that can generate neurons, astrocytes and oligodendrocytes.
In PNS:
- Schwann cells: Similar to oligodendrocytes in the CNS, they myelinate neurons in the PNS.
- Satellite cells: surround neurons in the sensory, sympathetic and parasympathetic ganglia and help regulate the chemical environment. They may contribute to chronic pain.
- Enteric glial cells: found in the nerves in the digestive system.

Neurotransmitters & Neurotransmission

There are 100 billion neurons in your brain.

Messages within the brain are delivered in many ways. The signals are transported through neurons along routes called pathways. Information is transferred between neurons through a process called neurotransmission.

the synapse—the place where a signal passes from the neuron to another cell; contact points between the axon terminals on one side and dendrites or cell bodies on the other. Here, in a 20-40 nanometre-wide gap, electrical signals coming via the axon are converted into chemical signals through the release of neurotransmitters, and then promptly converted back into electricity as information moves from neuron to neuron
the neurotransmission process: An electrical message, called an action potential, travels from the dendrites through the cell body and to the end of the axon. When the signal reaches the end of the axon it stimulates the release of tiny sacs called vesicles. These vesicles release neurotransmitters into the synaptic cleft. The neurotransmitters cross the synapse and attach to receptors (special places on the dendrites of the next neuron). The neurotransmitters fit into the receptors like keys in locks. Once the neurotransmitter has attached to the receptors of the second neuron, the message is passed on. The neurotransmitters are released from the receptors and are either broken down or go back into the axon of the first neuron.

Neurotransmitters transmit one of three possible actions in their messages, depending on the specific neurotransmitter.

Excitatory: “excite” the neuron and cause it to “fire off the message,” meaning, the message continues to be passed along to the next cell. Examples include glutamate, epinephrine and norepinephrine.
Inhibitory: block or prevent the chemical message from being passed along any farther. Gamma-aminobutyric acid (GABA), glycine and serotonin are examples.
Modulatory: influence the effects of other chemical messengers. They “tweak” or adjust how cells communicate at the synapse. They also affect a larger number of neurons at the same time.

Neuroplasticity

Fun fact: Thought alone is associated with neuroplastic gains. Some aging piano performers prepare for concerts primarily through visualization instead of physical practice. Both approaches show the same motor mapping in an fMRI scan.

Neuroplasticity, also known as neural plasticity or brain plasticity, is a process that involves adaptive structural and functional changes to the brain. It is defined as the ability of the nervous system to change its activity in response to intrinsic or extrinsic stimuli by reorganizing its structure, functions, or connections. These neuroplastic changes, which work with one another, occur at the chemical, structural and functional levels of the brain. Here's how:

Chemical change occurs in the initial stages of learning something new, and primarily influences short-term memory or short-term improvement in a motor skill. Structural change occurs when neurons in the brain change their connections, altering your brain's structure. This type of change requires more effort and time, and involves long-term memory and long-term improvement of a motor skill. Functional change occurs when entire brain networks change. As they are used over and over again, these brain networks become more excitable and more efficient when activated.

Although some neural functions appear to be hard-wired in specific areas of the brain, certain neural networks that carry out specific functions exhibit adaptive traits of being able to deviate from their usual functions and to reorganize themselves. Rapid change or reorganization of the brain’s neural networks can take place in many different forms and under many different circumstances. The brain is constantly processing sensory information, and as it does, over time, some synapses strengthen and others weaken, depending on which are used. Eventually, some unused synapses are destroyed completely, a process known as synaptic pruning, which leaves behind only the efficient networks of neural connections.

Other forms of neuroplasticity work the same way, but under different circumstances and sometimes only to a limited extent. For example, the loss of a limb or the loss of hearing would alter the balance of sensory information received by the brain. The brain would also attempt to compensate for lost activity after physical damage to the brain such as after a stroke. Finally, neuroplasticity is used during the reinforcement of sensory information through experiences and learning. The same brain mechanisms operate in all of these situations- it is adjusting the strength or number of synapses between neurons. These reorganizations can be either positive or negative, and it is all up to us! There are five main types of neuroplasticity.

Developmental plasticity happens mostly in the first few years of life as neurons grow very rapidly and send out multiple branches, forming too many connections. The connections that aren’t reinforced by sensory stimulation eventually weaken, and the connections that are reinforced become stronger. At birth, each neuron in the cerebral cortex has about 2,500 synapses. By the time you are 2 or 3 years old, the number of synapses is approximately 15,000 per neuron. This is about twice that of the average adult brain.

Homologous area adaptation is a type of neuroplasticity that occurs during an early critical period of development where a part of the brain is injured and the corresponding region in the opposite hemisphere of the brain takes over the function. The downside is that it may come at costs to functions that are normally stored here but now have to make room for the new functions.

Compensatory masquerade is the type of neuroplasticity that the brain uses when it figures out another way to get something done when the way we can’t do it the way we usually do after an injury, such as a stroke or brain injury. For example, most people, for the most part, have an intuitive sense of direction and distance they use when they’re driving. However, a person who has an impaired spatial sense will resort to another strategy, such as memorizing landmarks. The only change that occurs in the brain is a reorganization of neuronal networks that are already there.

Cross-modal reassignment is a specific type of neuroplasticity that is compensatory for a person who has lost a sense. For example, a blind person being able to “see”, or form a representation of an object in their mind, by touch rather than sight. The brain is able to do this because neurons with one another in the same abstract “language” of electrochemical impulses regardless of sensory input. In addition, all the sensory cortices of the brain have a similar six-layer processing structure. Because of this, the visual cortices of blind people can still create images of the physical world, but base these representations on input from another sense (touch). This is not just one area of the brain compensating for a lack of vision, it is a change in the actual functional assignment of a local brain region.

Map extension, simply put, is the type of neuroplasticity referred to when the brain area involved in a specific process or task expands as a result of learning and repetition. The arrangement of these areas in the cerebral cortex is referred to as a “map.” When you do something repeatedly, the area of the cortical map dedicated to this function grows and shrinks as you continue to “exercise” it. The more the brain is exercised, the stronger and more connected it becomes. The connections occur across the brain’s gray and white matter. This happens during the learning and practicing of a skill (e.g. playing a musical instrument). The region grows as you gain implicit familiarity with the skill and then shrinks to baseline once the learning becomes explicit. Implicit learning is the passive acquisition of knowledge through exposure to information, whereas explicit learning is the active acquisition of knowledge gained by consciously seeking out information. But as you continue to develop the skill with repeated practice, the region retains the initial enlargement. Map expansion neuroplasticity has also been observed in association with pain in the phenomenon of phantom limb syndrome.

Gray Matter & White Matter

Fun Facts:

Learning another language increases density in gray matter and strengthens white matter.

London taxi cab drivers have greater gray matter volume in mid-posterior hippocampus in comparison to London bus drivers.

Approximately 40% of your brain consists of gray matter and 60% is made of white matter, but both are essential. Gray matter is composed mostly of neuron cell bodies and their dendrites. White matter is mostly made up of long axons that transmit impulses to more distant regions of your brain and spinal cord. Gray matter is primarily responsible for processing and interpreting information. It is the seat of a human’s unique ability to think and reason. It is the place where the processing of sensation, perception, voluntary movement, learning, speech and cognition takes place. White matter’s role is to transmit that information between different gray matter areas to other parts of the nervous system and the rest of your body. Gray matter gets its color from a high concentration of cell bodies of neurons. White matter gets its color from the myelin sheath, a protective coating over the axons.

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