Neuroscience Glossary

Action potential: A brief electrical signal that travels along a neuron's axon, forming the basic unit of information transmission in the nervous system.
Amygdala: An almond-shaped structure in the medial temporal lobe central to fear, threat detection, and emotional memory. See the full Amygdala article.
Aphasia: A language disorder, usually caused by stroke or brain injury, that impairs the ability to produce or understand speech and writing.
Astrocyte: A star-shaped type of glial cell that supports neurons structurally and metabolically, helps regulate the blood-brain barrier, and assists in repairing brain tissue.
Autonomic nervous system: The part of the peripheral nervous system that regulates involuntary functions such as heart rate, digestion, and breathing.
Axon: The long, slender projection of a neuron that carries electrical signals away from the cell body toward other neurons.
Basal ganglia: A group of deep brain structures involved in initiating and smoothing voluntary movement; central to Parkinson's disease pathology.
Bilateral: Occurring on, or affecting, both sides of the brain or body.
Brain stem: The stalk connecting the brain to the spinal cord, controlling vital functions like breathing and heart rate. See the full Brain Stem article.
Broca's area: A region typically in the left frontal lobe responsible for producing fluent, grammatically organised speech.
Central nervous system (CNS): The brain and spinal cord together, which process and coordinate information for the entire body.
Cerebral cortex: The brain's outer layer of grey matter, responsible for higher-order functions like thought, perception, and voluntary movement.
Cerebrospinal fluid (CSF): A clear fluid that cushions the brain and spinal cord, removes waste, and helps regulate pressure within the skull.
Cerebrum: The largest part of the brain, made up of the left and right hemispheres and encompassing the cerebral cortex.
Cognitive function: Mental processes such as attention, memory, language, and reasoning that together enable thinking and understanding.
Consciousness: The state of being aware of and able to perceive one's surroundings, thoughts, and existence; thought to depend heavily on the thalamus, brain stem, and cortex working together.
Contralateral: Relating to the opposite side - for example, the left motor cortex controls movement on the contralateral (right) side of the body.
Corpus callosum: A dense band of nerve fibres connecting the brain's two hemispheres. See the full Corpus Callosum article.
Cortex: A general term for the brain's outer layer of tissue; usually refers to the cerebral cortex.
Dementia: A general term for a decline in memory, thinking, and reasoning severe enough to interfere with daily life; Alzheimer's disease is its most common cause.
Dendrite: A branching extension of a neuron that receives signals from other neurons and relays them toward the cell body.
Dopamine: A neurotransmitter involved in movement, motivation, and reward; its loss in the midbrain underlies the motor symptoms of Parkinson's disease.
Electroencephalography (EEG): A technique that records the brain's electrical activity via electrodes on the scalp, commonly used to detect and study seizures.
Executive function: A set of higher-order cognitive processes - planning, impulse control, working memory, and task-switching - largely governed by the prefrontal cortex.
Frontal lobe: The brain's largest lobe, involved in decision-making, personality, and voluntary movement. See the full Frontal Lobe article.
Glia (glial cells): Non-neuronal support cells in the nervous system that provide structural support, insulation, nutrients, and immune defence for neurons.
Grey matter: Brain tissue made up mostly of neuron cell bodies, found in the cortex and various deep nuclei.
Hemisphere: One of the two symmetrical halves of the cerebrum (left and right), connected by the corpus callosum.
Hippocampus: A seahorse-shaped structure in the temporal lobe essential for forming new memories and spatial navigation. See the full Hippocampus article.
Homunculus: A distorted map of the body used to illustrate how much cortical territory the motor or sensory cortex devotes to each body part.
Ipsilateral: Relating to the same side - the opposite of contralateral.
Limbic system: A group of interconnected structures, including the hippocampus and amygdala, involved in memory and emotion.
Magnetic resonance imaging (MRI): A non-invasive imaging technique using magnetic fields to produce detailed images of brain structure, widely used in both research and diagnosis.
Medulla oblongata: The lowest part of the brain stem, controlling essential functions such as breathing, heart rate, and blood pressure.
Motor cortex: A strip of cortex at the back of the frontal lobe that initiates voluntary movement, organised as a body map (the motor homunculus).
Myelin: A fatty insulating layer wrapped around many axons that dramatically speeds up electrical signal transmission.
Neurodegeneration: The progressive loss of structure or function of neurons, underlying conditions such as Alzheimer's and Parkinson's disease.
Neuron: A specialised nerve cell that transmits information via electrical and chemical signals; the basic building block of the nervous system.
Neuroplasticity: The brain's ability to reorganise itself - forming new connections or strengthening existing ones - in response to learning, experience, or injury.
Neurotransmitter: A chemical messenger released by neurons to transmit signals across a synapse to another neuron, muscle, or gland.
Occipital lobe: The brain's primary visual processing centre, located at the back of the cerebral cortex. See the full Occipital Lobe article.
Parietal lobe: A cerebral lobe that integrates sensory information and supports spatial awareness. See the full Parietal Lobe article.
Peripheral nervous system (PNS): All nerves outside the brain and spinal cord, connecting the central nervous system to the limbs and organs.
Prefrontal cortex: The foremost part of the frontal lobe, central to planning, judgment, impulse control, and personality.
Proprioception: The sense of the body's own position and movement in space, relying heavily on the parietal lobe and cerebellum.
Semantic memory: Long-term memory for general facts and concepts about the world, as distinct from memory for personal experiences.
Somatosensory cortex: A strip of the parietal lobe that processes touch, temperature, and pain signals from across the body.
Synapse: The junction between two neurons where electrical signals are converted to chemical signals (via neurotransmitters) and back again.
Temporal lobe: A cerebral lobe responsible for hearing, language comprehension, and memory. See the full Temporal Lobe article.
Thalamus: A central relay structure that routes nearly all sensory and motor signals to the cerebral cortex. See the full Thalamus article.
Vestibular system: The sensory system, based in the inner ear, that detects balance and spatial orientation, working closely with the cerebellum.
Wernicke's area: A region typically in the left temporal lobe essential for language comprehension.
White matter: Brain tissue made up mostly of myelinated axons, which connect different grey matter regions; the corpus callosum is a major white matter structure.