Glossary of Neuroscience Terms

Glossary of Neuroscience Terms

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Addiction is a brain disorder characterized by compulsive engagement in rewarding stimuli despite adverse consequences. Despite the involvement of a number of psychosocial factors, a biological process—one that is induced by repeated exposure to an addictive stimulus—is the core pathology that drives the development and maintenance of addiction, according to the "brain disease model" of addiction.

Adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex that produces steroid hormones and an inner medulla.

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.

Allele. One of two or more varying forms of a gene due to genetic mutation.

Alzheimer's disease (AD), also referred to simply as Alzheimer's, is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events.

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 neurotransmitter is an amino acid that is able to transmit a nerve message across a synapse. Neurotransmitters (chemicals) are packaged into vesicles that cluster beneath the axon terminal membrane on the presynaptic side of a synapse in a process called endocytosis.

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.

Anxiety. Feelings of intense and persistent worry or fear regarding everyday situations.

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

Astrocytes, also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord.

Atkinson–Shiffrin model (also known as the multi-store model or modal model) is a model of memory proposed in 1968 by Richard Atkinson and Richard Shiffrin. The model asserts that human memory has three separate components: a sensory register, where sensory information enters memory, a short-term store, also called working memory or short-term memory, which receives and holds input from both the sensory register and the long-term store, and a long-term store, where information which has been rehearsed (explained below) in the short-term store is held indefinitely.

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.

Autonomic nervous system (ANS), formerly the vegetative nervous system, is a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs. The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is the primary mechanism in control of the fight-or-flight response.

Axon, or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body.

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 (or basal nuclei) are a group of subcortical nuclei, of varied origin, in the brains of vertebrates.

Biomarkers. A measurable physiological indicator of a biological state or condition.

Bipolar disorder, previously known as manic depression, is a mood disorder characterized by periods of depression and periods of abnormally elevated mood that last from days to weeks each.

Brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion.

Brain-computer interface. A device or program that permits direct or indirect collaboration between the brain and a computer system.

Brain games. Brain training (also called cognitive training) is a program of regular activities purported to maintain or improve one's cognitive abilities. The phrase “cognitive ability” usually refers to components of fluid intelligence such as executive function and working memory. Cognitive training reflects a hypothesis that cognitive abilities can be maintained or improved by exercising the brain, analogous to the way physical fitness is improved by exercising the body.

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.

Brain stem is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord.

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

Broca's area, or the Broca area, is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions 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 dendrites connect to this part of the cell.

Central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals—i.e., all multicellular animals except sponges and jellyfish.

Central sulcus is a sulcus, or groove, in the cerebral cortex in the brains of vertebrates.

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.

Cerebrum, telencephalon, or endbrain, is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb.

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

Cochlea is the part of the inner ear involved in hearing.

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

Cognitive neuroscience. The field of study 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.

Corpus callosum. The collection of nerve fibers connecting the two cerebral hemispheres.

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

Cortisol. 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.


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.

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.

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, also dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project.

Depression. A mood or affective disorder characterized by sadness and lack of motivation.

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.

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

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

Dyslexia. 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.

Endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs.

Endorphins. Hormones produced by the brain, in response to pain or stress, to blunt the sensation of pain.

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

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


Fissure. A groove or indentation observed in the brain.

Frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove between tissues called the central sulcus and from the temporal lobe by a deeper groove called the lateral sulcus (Sylvian fissure). The most anterior rounded part of the frontal lobe (though not well-defined) is known as the frontal pole, one of the three poles of the cerebrum.

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.

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.


Gamma-aminobutyric acid (GABA). A neurotransmitter implicated in brain development, muscle control, and reduced stress response.

Gene is a basic unit of heredity and a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein.

Gene expression. The process by which a gene’s nucleotide sequence is transcribed into the form of RNA—often as a prelude to being translated into a protein.

Gene mapping. Determining the relative positions of genes on a chromosome and the distance between them.

Genome. The complete genetic map for an organism. In humans, this includes about 30,000 genes, more than 15,000 of which relate to functions of the brain.

Glia, also called glial cells or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses.

Glioma is a type of tumor that starts in the glial cells of the brain or the spine.

Glucose. A natural sugar that is carried in the blood and is the principal source of energy for the cells of the brain and body.

Gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci. Gyri and sulci create the folded appearance of the brain in humans and other mammals.


Hemisphere. In brain science, refers to either half of the brain (left or right). The two hemispheres are separated by a deep groove, or fissure, down the center.

Hippocampus is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation.

Hormone is any member of a class of signaling molecules in multicellular organisms, that are transported to distant organs to regulate physiology and behavior.

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.

Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system.


In silico. An experimental method to study brain or neural function using computer modeling 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.

Information can be thought of as the resolution of uncertainty; it answers the question of "What an entity is" and thus defines both its essence and the nature of its characteristics. The concept of information has different meanings in different contexts. Thus the concept becomes synonymous to notions of constraint, communication, control, data, form, education, knowledge, meaning, understanding, mental stimuli, pattern, perception, proposition, representation, and entropy. Information is associated with data. The difference is that information resolves uncertainty. Data can represent redundant symbols, but approaches information through optimal data compression.

Intelligence has been defined in many ways: the capacity for logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can be described as the ability to perceive or infer information, and to retain it as knowledge to be applied towards adaptive behaviors within an environment or context.

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

Ions. Atoms or small groups of atoms that carry an electric charge, either positive or negative.

Ion channel. A pore in the membrane of a neuron that allows ions to pass through, helping to shape action potentials.


Ketamine is a medication primarily used for starting and maintaining anesthesia. It induces dissociative anesthesia, a trance-like state providing pain relief, sedation, and amnesia

Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts (descriptive knowledge), skills (procedural knowledge), or objects (acquaintance knowledge). By most accounts, knowledge can be acquired in many different ways and from many sources, including but not limited to perception, reason, memory, testimony, scientific inquiry, education, and practice. The philosophical study of knowledge is called epistemology.


Learning is the process of acquiring new understanding, knowledge, behaviors, skills, values, attitudes, and preferences. The ability to learn is possessed by humans, animals, and some machines; there is also evidence for some kind of learning in certain plants.

Lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma.

Limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.

Long-term memory (LTM) is the stage of the Atkinson–Shiffrin memory model where informative knowledge is held indefinitely. It is defined in contrast to short-term and working memory, which persist for only about 18 to 30 seconds. Long-term memory is commonly labelled as explicit memory (declarative), as well as episodic memory, semantic memory, autobiographical memory, and implicit memory (procedural memory).

Long term potentiation (LTP). The persistent strengthening of a synapse with increased use, thought to underlie learning and memory.


Machine learning. Also referred to as deep 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.

Magnetic resonance imaging (MRI). A non-invasive imaging technology, often used for brain imaging. An MRI scanner includes intensely powerful magnets, typically 10,000 to 40,000 times as strong as the Earth’s magnetic field.

Manic-depressive disorder. See bipolar disorder.

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

Melatonin is a hormone primarily released by the pineal gland at night, and has long been associated with control of the sleep–wake cycle.

Memory is the faculty of the brain by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, it would be impossible for language, relationships, or personal identity to develop. Memory loss is usually described as forgetfulness or amnesia. Declarative, or explicit, memory is the conscious storage and recollection of data. Under declarative memory resides semantic and episodic memory. Semantic memory refers to memory that is encoded with specific meaning, while episodic memory refers to information that is encoded along a spatial and temporal plane. Declarative memory is usually the primary process thought of when referencing memory. Non-declarative, or implicit, memory is the unconscious storage and recollection of information.

Mental health. Referring to one’s psychological, emotional, and social well-being.

Mental math (Mental calculation) consists of arithmetical calculations using only the human brain, with no help from any supplies (such as pencil and paper) or devices such as a calculator.

Metabolism is the set of life-sustaining chemical reactions in organisms. The three main purposes of metabolism are: the conversion of food to energy to run cellular processes; the conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of metabolic wastes.

Microbiota are "ecological communities of commensal, symbiotic and pathogenic microorganisms" found in and on all multicellular organisms studied to date from plants to animals. Microbiota include bacteria, archaea, protists, fungi and viruses.

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

Midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation.

Molecular biology is the branch of biology that concerns the molecular basis of biological activity in and between cells, including molecular synthesis, modification, mechanisms and interactions.

Mood. A state of mind or feeling. In neuroscience, depression and anxiety are considered mood disorders, for example.

Motor cortex is the region of the cerebral cortex involved in the planning, control, and execution of voluntary movements. Classically, the motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus.

Mutation. A permanent structural alteration to DNA that modifies its previous nucleotide sequence.

Myelin is a lipid-rich (fatty) substance that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon.


Narcotic. A synthetic chemical compound that mimics the action of the body’s natural endorphins—hormones secreted to counteract pain.

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 cell. See neuron.

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 is a highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body.

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

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.

Neuroeducation. Sometimes referred to as educational neuroscience, this collaborative, interdisciplinary field of study uses findings in cognitive neuroscience to inform teaching and other educational practices.

Neuroethics. An interdisciplinary field of study that addresses the ethical implications of our increased ability to understand and change the brain. Enhanced cognitive performance, life extension, the use of neuroscience in marketing, and many other issues are included in this ongoing social-scientific debate.

Neurogenesis is the process by which nervous system cells, the neurons, are produced by neural stem cells (NSCs). It occurs in all species of animals except the porifera (sponges) and placozoans.

Neuroimmunology is a field combining neuroscience, the study of the nervous system, and immunology, the study of the immune system.

Neuroplasticity, also known as neural plasticity, or brain plasticity, is the ability of neural networks in the brain to change through growth and reorganization. These changes range from individual neuron pathways making new connections, to systematic adjustments like cortical remapping.

Neuron or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. It is the main component of nervous tissue in all animals except sponges and placozoa. Plants and fungi do not have nerve cells. Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. A group of connected neurons is called a neural circuit.

Neuroscience (or neurobiology) is the scientific study of the nervous system.

Neurotransmitters are chemical messengers that transmit a signal from a neuron across the synapse to a target cell, which can be a different neuron, muscle cell, or gland cell. Neurotransmitters are chemical substances made by the neuron specifically to transmit a message

Nucleotide. Sometimes referred to as a nucleic acid, these are the biological building blocks of DNA.

Nucleotide sequence. A specific and ordered array of nucleotides that make up a specific genetic variant or allele.

Nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the nucleus accumbens septi) is a region in the basal forebrain rostral to the preoptic area of the hypothalamus. The nucleus accumbens and the olfactory tubercle collectively form the ventral striatum. The ventral striatum and dorsal striatum collectively form the striatum, which is the main component of the basal ganglia.


Obsessive compulsive disorder (OCD). A form of anxiety disorder characterized by unreasonable thoughts, or obsessions, which result in compulsive, repetitive behaviors.

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, also known as cranial nerve II, or simply as CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus.

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

Oxytocin (Oxt) is a peptide hormone and neuropeptide. It is normally produced in the hypothalamus and released by the posterior pituitary.


Parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory information among various modalities, including spatial sense and navigation (proprioception), the main sensory receptive area for the sense of touch in the somatosensory cortex which is just posterior to the central sulcus in the postcentral gyrus, and the dorsal stream of the visual system. The major sensory inputs from the skin (touch, temperature, and pain receptors), relay through the thalamus to the parietal lobe.

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.

Perception. The way the brain organizes, processes, and interprets sensory information to give rise to our ability to make sense of and navigate the world around us.

Peripheral nervous system. The nervous system outside the brain and spinal cord.

Peripheral vision or indirect vision, is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the visual field is included in the notion of peripheral vision.

Persistent vegetative state. A disorder of consciousness, often following severe brain trauma, in which an individual has not even minimal conscious awareness. The condition can be transient, marking a stage in recovery, or permanent.

Pituitary gland, or hypophysis, is an endocrine gland, about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain.

Plasticity. In neuroscience, refers to the brain’s capacity to change and adapt in response to developmental forces, learning processes, injury, or aging.

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.

Postsynaptic cell. The neuron on the receiving end of a nerve impulse transmitted from another neuron.

Post-traumatic stress disorder (PTSD). A mental disorder that develops in response to a traumatic event such as combat, sexual assault, or abuse. Symptoms can include mood disturbances, hyperarousal, memory flashbacks, sleep problems, anxiety, and depression.

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.

Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions.

Psychology is the science of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, as well as feelings and thought. It is an academic discipline of immense scope. Psychologists also seek an understanding of the emergent properties of brains, linking the discipline to neuroscience. As a social science, psychologists aim to understand the behavior of individuals and groups.

Psychosis is an abnormal condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations.


Rapid eye movement (REM) sleep. A stage of sleep occurring approximately 90 minutes after sleep onset characterized by increased brain activity, rapid eye movements, and muscle relaxation.

Reading is the process of taking in the sense or meaning of letters, symbols, etc., especially by sight or touch. For educators and researchers, reading is a multifaceted process involving such areas as word recognition, orthography (spelling), alphabetics, phonics, phonemic awareness, vocabulary, comprehension, fluency, and motivation.

Reading speed (Words per minute). Words per minute, commonly abbreviated wpm (sometimes uppercased WPM), is a measure of words processed in a minute, often used as a measurement of the speed of typing, reading or Morse code sending and receiving.

Receptors. Molecules on the surfaces of neurons whose structures precisely match those of chemical messengers (such as neurotransmitters or hormones) released during synaptic transmission. The chemicals attach themselves to the receptors, in lock-and-key fashion, to activate the receiving cell structure.

Recovery of function. The ability of the nervous system to repair or compensate for damage to the brain or nervous system after insult or injury in order to regain function.

Regression (in reading) is the process of re-reading text that you’ve already read. It goes by other names including back-skipping, re-reading, and going back over what you’ve read.

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.

Retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to the brain to create visual perception. The retina serves a function analogous to that of the film or image sensor in a camera.

Reuptake is the reabsorption of a neurotransmitter by a neurotransmitter transporter located along the plasma membrane of an axon terminal (i.e., the pre-synaptic neuron at a synapse) or glial cell after it has performed its function of transmitting a neural impulse.

RNA (ribonucleic acid). A chemical similar to a single strand of DNA. The sugar is ribose, not deoxyribose, hence RNA. RNA delivers DNA’s genetic message to the cytoplasm of a cell, where proteins are made.

Rod. A type of photoreceptor, usually found on the outer edges of the retina, that helps facilitate peripheral vision.


Saccade is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction.

Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking.

Senses. The bodily organs that provide critical information for perception and behavior from the outside world. The five classic senses are: sight, hearing, taste, touch, and smell.

Serotonin is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction

Short-term memory (or "primary" or "active memory") is the capacity for holding, but not manipulating, a small amount of information in mind in an active, readily available state for a short period of time. For example, short-term memory can be used to remember a phone number that has just been recited. The duration of short-term memory (when rehearsal or active maintenance is prevented) is believed to be in the order of seconds.

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

Soma. See cell body.

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

Sono-stimulation. The activation of neural networks using ultrasound.

Skimming is a reading technique to get a general overview of the material. The main idea of skimming is skipping less critical text, for example, lengthy descriptions, samples, etc.

Speed reading is any of several techniques claiming to improve one's ability to read quickly. Speed-reading methods include chunking and minimizing subvocalization. The many available speed-reading training programs may utilise books, videos, software, and seminars.

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.

Stem cells. are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage.

Stress. Physical, emotional, and mental factors that result in bodily or psychological tension. Chronic stress is linked to issues with mental and physical health.

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.

Subgenual cortex. The region in the back of the frontal lobes, found below the corpus callosum, which has been implicated in mood states.

Subthalamic nucleus. A small brain structure, located in the basal ganglia, that plays an important role in coordinating movement. It is the most common target for neuromodulation techniques, like deep brain stimulation, to help diminish the symptoms of Parkinson’s disease.

Subvocalization, or silent speech, is the internal speech typically made when reading; it provides the sound of the word as it is read. This is a natural process when reading, and it helps the mind to access meanings to comprehend and remember what is read, potentially reducing cognitive load.

Sulcus. A shallower groove on the brain’s cerebrum (deeper grooves are called fissures).

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.

Synaptic transmission. The process of nerve-to-nerve communication in the central nervous system, whereby one neuron sends a chemical signal across the synaptic cleft to another neuron.


Telomere. The protective cap found at the end of a chromosome. Research studies suggest these caps may be shortened in neurodegenerative diseases.

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.

Thalamus is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, allowing hub-like exchanges of information. It has several functions, such as relaying of sensory signals, including motor signals to the cerebral cortex and the regulation of consciousness, sleep, and alertness.

Transcranial electrical stimulation (tDCS and tACS). A non-invasive procedure that applies electrical stimulation to the scalp to increase or decrease neural signaling.

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.


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


Vagus nerve, historically cited as the pneumogastric nerve, is the tenth cranial nerve or CN X, and interfaces with the parasympathetic control of the heart, lungs, and digestive tract.

Vertebral arteries. The major arteries of the neck, which merge to form the basilar artery.

Vestibular system. Regions in the body and brain that help support balance in movement.

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.

Vision span or perceptual span is a controversial concept referring to the angular span (vertically and horizontally), within which the human eye has sharp enough vision to perform an action accurately (reading or face recognition).


Wernicke's area, also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to Broca's area, which is involved in the production of language. It is traditionally thought to reside in Brodmann area 22, which is located in the superior temporal gyrus in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of right-handed individuals and 70% of left-handed individuals

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.

Word. In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be uttered in isolation with objective or practical meaning.

Working memory is a cognitive system with a limited capacity that can hold information temporarily. Working memory is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term memory, but some theorists consider the two forms of memory distinct, assuming that working memory allows for the manipulation of stored information, whereas short-term memory only refers to the short-term storage of information. Working memory is a theoretical concept central to cognitive psychology, neuropsychology, and neuroscience.


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


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