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A

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.

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 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.

amygdala

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.

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.

angiography

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.

artificial intelligence (AI)

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

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.

axon

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.

B

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.

biomarkers

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.

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 imaging

Refers to various techniques, such as magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), and positron emission tomography (PET), that enables viewing of brain tissue and structure and to reveal parts of the brain associated with behaviors or activities.

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 waves

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

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.

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.

C

cell body

Also known as the soma, this central part of the neuron contains the nucleus of the neuron. The axon and dendrites connect 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.

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.

cerebrum

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.

cognition

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

cognitive neuroscience

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

consciousness

The state of being aware of one’s feelings and surroundings; the totality of one’s thoughts, feelings, and impressions.

cortex

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

D

deep brain stimulation

A method of treating various neuropsychiatric and neurodegenerative disorders through small, controlled electric pulses 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.

dementia

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.

dendrites

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.

depolarisation

A change in cell membrane’s potential making it more positive. Achieved by increasing permeability to an ion with a Nernst potential above the rentinol-binding proteins.

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.

dopamine

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

E

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.

electroencephalography (EEG)

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

electrophysiology

The branch of physiology that studies the electrical properties of biological cells and tissues

endovascular

Meaning “inside the blood vessel”. Endovascular procedures use very small cuts and long, thin tubes called catheters, which are placed inside a blood vessel to repair it

event-related potential (ERP)

The measured brain response as a result of specific sensory, cognitive or motor event.

executive function

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

F

frontal lobe

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

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 40s and early 60s. 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

AKA 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

G

gray matter

The parts of the brain and spinal cord made up primarily of groups of neuron cell bodies (as opposed to white matter, which is composed mainly of myelinated nerve fibers).

gyrus

The ridges on the brain’s outer surface.

H

hippocampus

A primitive brain structure, located deep in the brain, that is critical for memory and learning.

Huntington’s disease

A neurodegenerative disorder that causes progressive death of neurons in the brain, resulting in severe movement and cognitive problems. The disorder is caused by the mutation of a single gene—and symptoms typically present when an individual is in his or her 30’s or 40’s.

hyperpolarization

A change in cell membrane’s potential making it more negative and inhibiting further action potentials by requiring a higher action potential threshold.

hypothalamus

A small structure located at the base of the brain, where signals from the brain and the body’s hormonal system interact.

I

in silico

An experimental method to study brain or neural function using computer modelling or computer simulation.

in vitro

An experimental method to study brain or neural function by looking at cells outside a living organism, for example, in a test tube or petri dish.

in vivo

An experimental method allowing scientists to study brain or neural function in a living organism.

J

Jugular Vein

Any of several veins of the neck that drain blood from the brain, face, and neck, returning it to the heart via the superior vena cava.

L

long term potentiation (LTP)

The persistent strengthening of a synapse with increased use, thought to underlie learning and memory.

M

machine learning

Machine learning is a type of artificial intelligence algorithm that can learn rules or identify diagnostic criteria from immense data sets of brain imaging or genetic information. These algorithms are becoming more prevalent in scientific research—and are also starting to be incorporated into translational neuroscience research and medical practice.

magnetic resonance imaging (MRI)

A non-invasive imaging technology, often used for brain imaging. An MRI scanner includes intensely powerful magnets. These magnets, combined with coils that send electromagnetic pulses into the scanned tissue, induce radio-frequency signals from individual hydrogen atoms within the tissue. The scanner records and processes these signals to create an image of the scanned tissue.

medulla oblongata

The lower part of the brain stem, responsible for life-regulating functions like breathing and heart rate.

memory

The encoding and storage of information, in a way that allows it to be retrieved later. In the brain, memory involves integrated systems of neurons in diverse brain areas, each of which handles individual memory-related tasks.

microglia

A small, specialized glial cell that operates as the first line of immune defense in the central nervous system.

midbrain

Also referred to as the mesencephalon, the midbrain is a small part of the brain stem that plays an important role in movement as well as auditory and visual processing.

motor cortex

The part of the brain’s cerebrum, just to the front of the central sulcus in the frontal lobe, that is involved in movement and muscle coordination. Scientists have identified specific spots in the motor cortex that control movement in specific parts of the body, the so-called “motor map.”

multiple sclerosis

A progressive neurodegenerative disease involving damage to the protective myelin sheaths of nerve cells in the brain and spinal cord. Symptoms include impaired movement, pain, and fatigue.

N

nerve growth factor

Also referred to as a neurotrophic factor, this special protein helps regulate the growth and survival of nerve cells. One of the most well-known of these is brain-derived neurotrophic factor (BDNF).

nerve impulse

Also referred to as a nerve signal, the way that a neuron communicates with other cells by transmitting an electrochemical signal down the length of the axon.

nervous system

The system in the body that processes and transmits signals from the brain to the rest of the body to facilitate movement and behavior. It consists of two parts, the central nervous system, or the brain and spinal cord, and the peripheral nervous system, the nerves that branch off from the spinal cord extending throughout the rest of the body.

neurodegenerative diseases

Diseases characterized by the progressive deterioration and death of nerve cells (neurodegeneration), typically originating in one area of the brain and spreading to other connected areas. Neurodegenerative diseases include amyotrophic lateral sclerosis (ALS), Huntington’s disease, Alzheimer’s disease, frontotemporal degeneration, and Parkinson’s disease.

neurodevelopmental disorder

Disorders or conditions arising from impairments during the development and maturation of the brain and/or nervous system. Neurodevelopmental disorders include schizophrenia and autism spectrum disorder.

neurodiagnostics

The science of using electrophysiology to monitor the functional integrity of neural structures, e.g. brain injury biomarkers.

neuroeconomics

An interdisciplinary field of study that uses neuroscientific research to help explain human decision-making behavior.

neuroethics

An interdisciplinary field of study that addresses the ethical implications of our increased ability to understand and change the brain.

neuromodulation

The alteration of nerve activity through targeted delivery of a therapeutic stimulus, e.g. Deep Brain Stimulation (DBS).

neuron

A nerve cell. The basic unit of the central nervous system, the neuron is responsible for the transmission of nerve impulses. Unlike any other cell in the body, a neuron consists of a central cell body as well as several threadlike “arms” called axons and dendrites, which transmit nerve impulses.

neuron firing rate

The study of the brain and nervous system, including their structure, function, and disorders.

neuroprosthetics

The restoration of a lost brain function, e.g. motor control or cognition

neuroscience

The study of the brain and nervous system, including their structure, function, and disorders.

neurovascular

A field of science involving the study of the brain and its comprising blood vessels.

O

occipital lobe

A part of the brain’s cerebrum, located at the rear of the brain, above the cerebellum. The occipital lobe is primarily concerned with vision and encompasses the visual cortex.

optic nerve

One of the twelve pairs of cranial nerves in the human body, the optic nerve transmits information from the retina, at the back of the eye, to the brain.

optogenetics

An innovative neuroscientific technique that uses light to turn genetically modified neurons on and off at will, in live animals.

P

P300

A characteristic spike in activity recorded approximately 300ms following presentation of target stimulus.

parietal lobe

The area of the brain’s cerebrum located just behind the central sulcus. It is concerned primarily with the reception and processing of sensory information from the body and is also involved in map interpretation and spatial orientation

Parkinson’s disease

A neurodegenerative disorder characterized by tremor, slowed movement, and speech changes due to the death of dopamine neurons located in the substantia nigra.

peripheral nervous system

The nervous system outside the brain and spinal cord.

positron emission tomography (PET)

An imaging technique, often used in brain imaging. For a PET scan of the brain, a radioactive “marker” that emits, or releases, positrons (parts of an atom that release gamma radiation) is injected into the bloodstream. Detectors outside of the head can sense these “positron emissions,” which are then reconstructed using sophisticated computer programs to create computer images.

prefrontal cortex

The area of the cerebrum located in the forward part of the frontal lobe, which mediates many of the higher cognitive processes such as planning, reasoning, and “social cognition”—a complex skill involving the ability to assess social situations in light of previous experience and personal knowledge, and interact appropriately with others. The prefrontal cortex is thought to be the most recently evolved area of the brain.

premotor cortex

The area of the cerebrum located between the prefrontal cortex and the motor cortex, in the frontal lobe. It is involved in the planning and execution of movements.

psychology

An academic or scientific field of study concerned with the behavior of humans and animals and related mental processes.

R

receptors

rehabilitation

The process by which people can repair, recover, or compensate for functional abilities after sustaining damage to the nervous system. Rehabilitation activities may include speech, physical, or occupational therapies.

reinforcement brain network

Also known as the mesolimbic circuit, this important network of brain regions stretching from the brain stem to the frontal lobes is implicated in risk and reward processing, as well as learning.

resting state

The state of the brain when it is not consciously engaged in an explicit task. Brain imaging techniques such as fMRI can be used to measure the residual activity that occurs in this state.

retina

The sensory membrane at the back of the eye that processes light information to facilitate sight.

S

social neuroscience

The field of study investigating the biological systems underlying social processes and behavior.

somatosensory cortex

Located in the parietal lobe, this region of the brain processes touch, pressure, and pain information.

spinal cord

The “other half” of the central nervous system (with the brain). The spinal cord is a cable that descends from the brain stem to the lower back. It consists of an inner core of gray matter surrounded by white matter.

ssvep

State-state visually evoked potential, or ssvep, is a signal that is a natural response to a visual stimulant at specific frequencies.

stent

a short narrow metal or plastic tube often in the form of a mesh that is inserted into the lumen of an anatomical vessel (such as an artery or a bile duct) especially to keep a previously blocked passageway open.

stroke

A neurological event that occurs when the blood supply to the brain is blocked, depriving the tissue of oxygen, or when there is a bleed into the brain due to the rupturing of an artery.

sulcus

A shallower groove on the brain’s cerebrum.

superior sagittal sinus vein

The superior sagittal sinus (also known as the superior longitudinal sinus), within the human head, is an unpaired area along the attached margin of the falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses.

synapse

The junction where an axon approaches another neuron or its extension (a dendrite); the point at which nerve-to-nerve communication occurs. Nerve impulses traveling down the axon reach the synapse and release neurotransmitters into the synaptic cleft, the tiny gap between neurons.

synaptic cleft

The small space between neurons where neurotransmitters are released.

synchronization

Synchronization, also referred to as neural oscillations, are the rhythmic or repetitive patterns of neural activity in the central nervous system that are the basis of thinking and consciousness.

T

temporal lobes

The parts of the cerebrum that are located on either side of the head, roughly beneath the temples in humans. These areas are involved in hearing, language, memory storage, and emotion.

transcranial electrical stimulation (tDCS and tACS)

A non-invasive procedure that applies electrical stimulation to the scalp to increase or decrease neural signaling. The two main types are direct current stimulation (tDCS) and alternating current stimulation (tACS). They are used for therapeutic purposes as well as to study cognitive processing.

transcranial magnetic stimulation (TMS)

A non-invasive procedure that uses the energy from a strong magnet to stimulate changes in neural processing from above the scalp. It is used as a treatment for depression as well as a research method to investigate cognitive processes.

traumatic brain injury (TBI)

An injury to the brain acquired when the head is violently shook, struck, or pierced by an object. A nearby blast or explosion, as may occur in combat, emits shock waves that can also cause a TBI. Moderate to severe TBI causes permanent impairments in brain function. Symptoms of mild TBI may include headache, dizziness, attention problems, or issues with behavior and mood.

U

ultrasound

An imaging technique that uses sound waves to visualize the inside of the body

V

vagus nerve

One of the twelve pairs of cranial nerves in the human body, the vagus nerve connects the brain stem to the body, transmitting information from the brain to the major organs and other tissues.

vagus nerve stimulation

A neuromodulation treatment that involves a small implant that electrically stimulates the vagus nerve, which runs from the brain stem to the abdomen. It is mostly used to treat epilepsy but is also being investigated as a potential treatment for depression, bipolar disorder, and Alzheimer’s disease.

visual cortex

The area of the cerebrum that is specialized for vision. It lies primarily in the occipital lobe at the rear of the brain and is connected to the eyes by the optic nerves.

W

White matter

Brain or spinal cord tissue consisting primarily of myelin-covered axons that extend from nerve cell bodies in the gray matter of the central nervous system.

X

X-ray

An imaging method that uses electromagnetic radiation to visualize the structures inside the body, particularly bones