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Key Neuroscience and Society Terms

Whether you're a student, educator, or simply curious about how the brain works, this glossary provides definitions for more than 350 terms to enhance your understanding of neuroscience and society.


Action potential

Sometimes called a “spike” or described as a neuron “firing,” an action potential occurs when there is a significant increase in the electrical activity along the membrane of a nerve cell. It is associated with neurons passing electrochemical messages down the axon, releasing neurotransmitters to neighboring cells in the synapse.


(legal sense) Evidence that is considered to be acceptable or valid for use in legal proceedings.


Now commonly called substance use disorder, addiction is a mental health condition where a person’s progressive and chronic use of drugs or alcohol leads to issues with personal relationships, the ability to work, and one’s physical health.

Adrenal glands

Located on top of each kidney, these two glands are involved in the body’s response to stress and help regulate growth, blood glucose levels, and the body’s metabolic rate. They receive signals from the brain and secrete several different hormones in response, including cortisol and adrenaline.


Also called epinephrine, this hormone is secreted by the adrenal glands in response to stress and other challenges to the body. The release of adrenaline causes a number of changes throughout the body, including the metabolism of carbohydrates to supply the body’s energy demands and increased arousal or alertness.


One of two or more varying forms of a gene due to genetic mutation. Differing alleles, which can be found at the same spot on a chromosome, produce variation in inherited characteristics such as hair color or blood type. A dominant allele is one whose physiological function—such as making hair blonde—occurs even when only a single copy is present (among the two copies of each gene that everyone inherits from their parents). A recessive allele’s traits only appear when two copies are present.

Alzheimer’s disease

A debilitating form of dementia, this progressive and irreversible neurodegenerative disease results in the development of protein plaques and tangles that damages neurons and interfere with neural signaling, ultimately affecting memory and other important cognitive skills.

Amino acid

A type of small organic molecule that has a variety of biological roles but is best known as the “building block” of proteins.

Amino acid neurotransmitters

The most prevalent neurotransmitters in the brain, these include glutamate and aspartate, which can increase the electrochemical activity of neurons, as well as glycine and gamma-amino butyric acid (GABA), which inhibit that electrochemical activity.


Part of the brain’s limbic system, this primitive brain structure lies deep in the center of the brain and is involved in emotional reactions, such as anger or fear, as well as emotionally charged memories. It also influences behavior such as feeding, sexual interest, and the immediate “fight or flight” stress reaction that helps ensure the person’s needs are met.

Amyloid-beta (Aβ) protein

A naturally occurring protein in brain cells. Large, abnormal clumps of this protein form the amyloid plaques that are a physiological hallmark of Alzheimer’s disease. Smaller groupings (oligomers) of Aβ seem more toxic to brain cells and are thought by many researchers to play an important role in the Alzheimer’s disease process.

Amyloid plaque

The sticky, abnormal accumulations of amyloid-beta protein aggregate around neurons and synapses in the memory and intellectual centers of the brain, in people with Alzheimer’s. These are sometimes referred to as neuritic plaques or senile plaques. While amyloid plaques have long been considered markers of Alzheimer’s, they are also found to some extent in many cognitively normal elderly people. The plaques’ role in Alzheimer’s neurodegeneration remains unclear.

Amyotrophic lateral sclerosis (ALS): 

Also known as Lou Gehrig’s disease, this neurodegenerative disease results in the death of brain cells that control the muscles.


A medical imaging technique that allows clinicians to visualize the interior of blood vessels, arteries, veins, and the heart.

Animal model

A laboratory animal that—through changes in its diet, exposure to toxins, genetic changes, or other experimental manipulations—mimics specific signs or symptoms of a human disease. Many of the most promising advances in treating brain disorders have come from research on animal models.

Anonymous data

Scientific or medical data which has been stripped of the pieces of the information that could identify the person who provided it.

Antidepressant medication

Classes of drugs that can treat depressive symptoms by affecting the levels of specific neurotransmitters in the brain. One of the most well-known types of antidepressant are selective serotonin reuptake inhibitors.


Feelings of intense and persistent worry or fear regarding everyday situations. While some feelings of anxiety are normal, they can be classified as an anxiety disorder when the symptoms start to interfere with daily living.


A form of programmed cell death that occurs as part of normal growth and development. However, in cases of brain disorders or disease, this natural process can be “hijacked,” resulting in the unnecessary death of crucial neurons.

Artificial intelligence (AI)

computer programs or systems designed to perform tasks that normally require human intelligence, including problem-solving, learning, and decision-making behaviors.


A star-shaped glial cell that supports neurons, by helping to both feed and remove waste from the cell, and otherwise modulates the activity of the neuron. Astrocytes also play critical roles in brain development and the creation of synapses.

Attention deficit hyperactivity disorder (ADHD)

A neurodevelopmental disorder that affects attention systems and impulse control. While ADHD is primarily known as a pediatric disorder, it also affects adults.

Auditory cortex

Part of the brain’s temporal lobe, this region is responsible for hearing. Nerve fibers extending from the inner ear carry nerve impulses generated by sounds into the auditory cortex for interpretation.

Autism spectrum disorder (ASD)

A neurodevelopmental disorder, with symptoms usually presenting within the first two years of life, characterized by issues of communication, personal interactions, and behavior. It is referred to as a spectrum disorder because of the variety in the type and severity of symptoms observed.

Autonomic nervous system

Part of the central nervous system that controls internal organ functions (e.g., blood pressure, respiration, intestinal function, urinary bladder control, perspiration, body temperature). Its actions are mainly involuntary.


The ability to make informed decisions freely (without coercion).


A long, single nerve fiber that transmits messages, via electrochemical impulses, from the body of the neuron to dendrites of other neurons, or directly to body tissues such as muscles.

Axon terminal

The very end of the axon, where electrochemical signals are passed through the synapse to neighboring cells by means of neurotransmitters and other neurochemicals. A collection of axons coming from, or going to, a specific brain area may be called a white matter fiber tract.


Basal ganglia

A group of structures below the cortex involved in motor, cognitive, and emotional functions.

Basilar artery

Located at the base of the skull, the basilar artery is a large, specialized blood vessel that supplies oxygenated blood to the brain and nervous system .

Belmont principles

The three principles—beneficence, distributive justice, and respect for persons—which  the 1976 Belmont Reportconcluded should underlie all conduct in biomedical and behavioral research in order to protect human participants.

Belmont Report

An influential report that identified and defined the basic ethical principles (the Belmont principles) that should govern research studies involving human participants. The report was developed by the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research.


One of the three Belmont principles, the requirement that physicians and researchers provide, to the best of their ability, positive benefits for patients that participate in clinical trials, including good health and the prevention and removal of harmful conditions.


Bioethics is the interdisciplinary study of ethical issues arising in the life sciences, health care, and health and science policy. (definition from the Hasting Center)


A measurable physiological indicator of a biological state or condition. For example, amyloid plaques—as detected on amyloid PET scans—are a biomarker of Alzheimer’s disease. Biomarkers can be used for both diagnostic and therapeutic purposes.

Bipolar disorder

Also known as manic depression or manic-depressive disorder, bipolar disorder is characterized by unpredictable changes in mood, as well as energy and activity levels, that can interfere with everyday tasks.

Blood-brain barrier

A protective barrier that separates the brain from the blood circulating across the body. The blood-brain barrier is semipermeable, meaning it allows the passage of water as well as molecules like glucose and other amino acids that help promote neural function.

Brain-computer interface

A device or program that permits direct or indirect collaboration between the brain and a computer system. For example, a device that harnesses brain signals to control a screen cursor or a prosthetic limb. Some systems can also translate the device’s actions or measurements back into a signal, creating a closed-loop system. Also called brain-machine interface.

Brain-derived neurotrophic factor (BDNF)

Sometimes referred to as “brain fertilizer,” BDNF is a protein that helps promote the growth, maintenance, and survival of neurons.

Brain imaging

Refers to various techniques, such as magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), and positron emission tomography (PET), that enable scientists to capture images of brain tissue and structure and to reveal what parts of the brain are associated with behaviors or activities. Structural brain imaging is concerned with identifying the anatomy of the brain and its changes with disease. Functional brain imaging is concerned with identifying the pattern of activity in the brain when people are at rest or when they are performing a task.

Brain implant (neural implant)

A medical device that connects the brain and technological devices to record, translate, or modify brain activity.

Brain organoid

A research model that uses pluripotent stem cells (iPSCs) to grow structures that resemble brains in some ways, but are grown in a lab dish made of neurons and other brain tissues.

Brain stem

A primitive part of the brain that connects the brain to the spinal cord, the brain stem controls functions basic to survival, such as heart rate, breathing, digestive processes, and sleeping.

Brain stimulation

The act of activating or inhibiting brain activity by using electricity, magnetism, or another form of medical device.

Brain tumor

A mass or growth of abnormal cells found in the brain. While people may commonly equate brain tumors with cancer, many tumors are benign—but their location in the brain can still interfere with normal brain function.

Brain waves

Rhythmic patterns of neural activity in the central nervous system, brain waves can also be called neural oscillations.

Broca’s area

Discovered by French physician Paul Broca in the late 19th century, this small region in the left frontal lobe has been linked to speech production.


Cell body

Also known as the soma, this central part of the neuron contains the nucleus of the neuron. The axon and dendritesconnect to this part of the cell.

Central nervous system

The brain and spinal cord constitute the central nervous system and are part of the broader nervous system, which also includes the peripheral nervous system.

Central sulcus

The primary groove in the brain’s cerebrum, which separates the frontal lobe in the front of the brain from the parietal and occipital lobes in the rear of the brain.

Cerebellar artery

The major blood vessel providing oxygenated blood to the cerebellum.


A brain structure located at the top of the brain stem that coordinates the brain’s instructions for skilled, repetitive movements and helps maintain balance and posture. Research suggests the cerebellum may also play a role, along with the cerebrum, in some emotional and cognitive processes.

Cerebral palsy

A developmental disorder resulting from damage to the brain before or during birth, usually characterized by impaired muscle coordination and body movements, but can also include impaired cognition and social behavior.

Cerebrospinal fluid (CSF) 

The clear, colorless liquid found surrounding the brain and spinal cord. This fluid can be analyzed to detect diseases.


The cerebrum is the largest brain structure in humans, accounting for about two-thirds of the brain’s mass and positioned over and around most other brain structures. The cerebrum is divided into left and right hemispheres, as well as specific areas called lobes that are associated with specialized functions.


A single organism with cells from more than one distinct genotype.


A threadlike structure of nucleotides that carries an organism’s genes or genetic information.

Chronic encephalopathy syndrome (CES)

Symptoms, including memory issues, depression, and impulsive behavior, that manifest themselves after repeated brain traumas. Over time, CES can result in a diagnosis of chronic traumatic encephalopathy (CTE).

Chronic traumatic encephalopathy (CTE)

Once known as dementia pugilistica and thought to be confined largely to former boxers, this neurodegenerative disease, with symptoms including impulsivity, memory problems, and depression, affects the brains of individuals who have suffered repeated concussions and traumatic brain injuries.

Clinical trial

Research studies conducted to test the safety and efficacy of different therapeutic interventions.


An automatic control system in which an operation, process, or mechanism is regulated by feedback from the system itself.


The part of the inner ear that transforms sound vibrations into neural impulses.

Codes of ethics

A set of guiding principles intended to help members of a group behave in an honest, moral, and beneficial manner.


The act of compelling someone to participate in an action without their consent.


A general term that includes thinking, perceiving, recognizing, conceiving, judging, sensing, reasoning, and imagining.

Cognitive enhancement

Various interventions (drugs, devices, therapies) that lead to improvement in abilities like memory, attention, information processing, problem solving, and decision-making.

Cognitive neuroscience

The field of study that investigates the biological processes in the brain that underlie attention, memory, and other facets of cognition.

Computational neuroscience

An interdisciplinary field of study that uses information processing properties and algorithms to further the study of brain function and behavior.

Computed tomography (CT or CAT)

An X-ray technique introduced in the early 1970s that enables scientists to take cross-sectional images of the body and brain. CT uses a series of X-ray beams passed through the body to collect information about tissue density, then applies sophisticated computer and mathematical formulas to create an anatomical image from the data.


A type of mild traumatic brain injury resulting from a blow or hit to the head that causes the brain to move rapidly back and forth inside the skull.


A type of photoreceptor cell responsible for color vision that is found in the retina.


A detailed map of the myriad neural connections (also called fiber tracts) that make up the brain and nervous system.


A being’s awareness of their own thoughts and feelings, as well as the state of the world around them.


A philosophical theory that says the rightness or wrongness of a particular behavior can only be determined by the outcome or consequences of it. Contrast with deontology

Corpus callosum

The collection of nerve fibers connecting the two cerebral hemispheres.


The outer layer of the cerebrum. Sometimes referred to as the cerebral cortex.


A steroid hormone produced by the adrenal glands that controls how the body uses fat, protein, carbohydrates, and minerals, and helps reduce inflammation. Cortisol is released in the body’s stress response; scientists have found that prolonged exposure to cortisol has damaging effects on the brain.


A person’s tendency to break the law or engage in criminal acts.

Critical period

A period of development during which an ability or characteristic is thought to be most easily learned or attained.

CRISPR (clustered regularly-interspaced short palindromic repeats)

A relatively precise and reliable DNA-editing technique.


Data governance

The policies, rules, and standards used to oversee how data is used in a particular environment.

Deep brain stimulation

A method of treating various neuropsychiatric and neurodegenerative disorders through small, controlled electric shocks administered from a special battery-operated neurostimulation implant. The implant, sometimes called a “brain pacemaker,” is placed within deep brain regions such as the globus pallidus or subthalamus.

Deep learning

See machine learning.

Default-mode network

The network indicates that the brain remains active even if not involved in a specific task. Even when you are daydreaming, the brain is in an active state.


General mental deterioration from a previously normal state of cognitive function due to disease or psychological factors. Alzheimer’s disease is one form of dementia.


Short nerve fibers that project from a neuron, generally receiving messages from the axons of other neurons and relaying them to the cell’s nucleus.


A philosophical theory that says the rightness or wrongness of a particular behavior should be determined by a set of existing rules, as opposed to the consequences of that action. Contrast with consequentialism


A mood or affective disorder characterized by sadness and lack of motivation. Depression has been linked to disruptions in one or more of the brain’s neurotransmitter systems, including those related to serotonin and dopamine.

Diagnostic and Statistical Manual of Mental Disorders (DSM)

The standard classification manual published by the American Psychiatric Association for mental health professionals to diagnose and treat mental disorders.


The biological process where immature, or undifferentiated cells, develop the specialized form and function of a particular phenotype.

Diffusion spectrum imaging (DSI)

A brain imaging method that detects the movement of water in tissue to help visualize the brain’s white matter. This approach typically allows better resolution than diffusion tensor imaging.

Diffusion tensor imaging (DTI)

A brain imaging method that helps visualize the brain’s white matter tracts by following the movement of water through tissues.

DNA (deoxyribonucleic acid) 

The material from which the 46 chromosomes in each cell’s nucleus is formed. DNA contains the codes for the body’s approximately 30,000 genes, governing all aspects of cell growth and inheritance. DNA has a double-helixstructure—two intertwined strands resembling a spiraling ladder.

Digital phenotyping

The use of data collected from personal electronic devices like smart phones to diagnose and monitor medical and psychiatric conditions.

Distributive justice

One of the three Belmont principles, fair or equal distribution of both the benefits and burdens involved with research.

Dominant gene

A gene that almost always results in a specific physical characteristic, for example a disease, even though the patient’s genome possesses only one copy. With a dominant gene, the chance of passing on the gene (and therefore the trait or disease) to children is 50-50 in each pregnancy.


A neurotransmitter involved in motivation, learning, pleasure, the control of body movement, and other brain functions.

Double helix

The structural arrangement of DNA, which looks something like an immensely long ladder twisted into a helix, or coil. The sides of the “ladder” are formed by a backbone of sugar and phosphate molecules, and the “rungs” consist of nucleotide bases joined weakly in the middle by hydrogen bonds.

Down syndrome

A genetic disorder characterized by intellectual impairment and physical abnormalities that arises from the genomehaving an extra copy of chromosome 21.

Dual use

Products or technologies that may be used for both civilian and military purposes.


A learning disorder that affects the ability to understand and produce language. It is commonly thought of as a reading disability, although it can affect other aspects of language.


Electroencephalography (EEG)

A method that measures electrical activity in the brain using small electrodes placed on the scalp.

Electroconvulsive therapy (ECT)

A therapeutic treatment for depression and other mental illnesses that sends small electric currents over the scalp to trigger a brief seizure.

Endocrine system

A system in the body composed of several different glands and organs that secrete hormones.


Hormones produced by the brain, in response to pain or stress, to blunt the sensation of pain. Narcotic drugs, such as morphine, imitate the actions of the body’s natural endorphins.


The person who uses a particular product or system.


A protein that facilitates a biochemical reaction. Organisms could not function if they had no enzymes.


A subset of genetics that focuses on how specific environmental factors can influence where, when, and how a gene is expressed, resulting in variation in the gene’s related traits.


A neurological disorder characterized by abnormal electrical activity in the brain, leading to seizures.


A 19th century scientific theory that advocated for selective mating of people with desirable hereditary traits.

Executive function

Higher level cognitive functions, including decision-making and judgment, involved with the control of behavior.



A groove or indentation observed in the brain.

Fragile X syndrome

A genetic disorder that interferes with brain development, leading to learning disabilities and cognitiveimpairment, particularly with regards to language.

Frontal lobe

The front of the brain’s cerebrum, beneath the forehead. This area of the brain is associated with higher cognitiveprocesses such as decision-making, reasoning, social cognition, and planning, as well as motor control.

Frontal operculum

The part of the frontal lobe that sits over the insula.

Frontotemporal degeneration (FTD) 

This is a common type of dementia caused by the loss of neurons in the frontal lobes. This disorder often strikes earlier than Alzheimer’s disease or other forms of dementia, with most patients diagnosed between their late 40’s and early 60’s. It also tends to present with more prominent behavior and social impairments as opposed to memory loss, though memory loss is common in later stages of disease.

Functional magnetic resonance imaging (fMRI)

A brain imaging technology, based on conventional MRI, that gathers information relating to short-term changes in oxygen consumption by cells in the brain. It typically uses this information to depict the brain areas that become more or less active—and presumably more or less involved—while a subject in the fMRI scanner performs a cognitive task.

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