Glossary 1 Flashcards
Acetylcholine
A critical neurotransmitter that controls functions such as memory, attention, sleep, heart rate, and muscular activity.
Action Potential
An electrical charge that travels along the axon to the neuron’s terminal, where it triggers the release of a neurotransmitter. This occurs when a neuron is activated and temporarily reverses the electrical state of its interior membrane from negative to positive.
Addiction
Loss of control over drug intake or compulsive seeking and taking of drugs, despite adverse consequences.
Adenosine
A neurochemical that inhibits wakefulness, serving the purpose of slowing down cellular activity and diminishing arous¬al. Adenosine levels decrease during sleep.
Adrenal Gland
An endocrine organ that secretes hormones. The outer layer (adrenal cortex) secretes the stress hormone cortisol. The inner portion (adrenal medulla) secretes epinephrine and norepinephrine in concert with the activation of the sympathetic nervous system in the “fight or flight” response.
Alzheimer’s Disease (AD)
A major cause of dementia in the elderly, this neurodegener¬ative disorder is characterized by the death of neurons in the hippocampus, cerebral cortex, and other brain regions. The earliest symp¬toms of the disease include forgetfulness; dis¬orientation as to time or place; and difficulty with concentration, calculation, language, and judgment. In the final stages, individuals are incapable of self-care and may be bedridden.
Amnesia
A memory impairment usually caused by brain damage or disease, or by drugs such as some anesthetics. People with amnesia may be unable to recall events from the past, form new memories, or both.
Amygdala
A structure in the forebrain that is an important component of the limbic system and plays a central role in emotional learning, particularly within the context of fear.
Amyotrophic Lateral Sclerosis (ALS)
Commonly known as Lou Gehrig’s disease, ALS causes motor neurons in the brain and spinal cord to disintegrate, resulting in loss of control of voluntary muscle movements such as walking.
Analgesic
A drug that relieves pain without causing a loss of consciousness.
Anxiety
A state of heightened arousal charac¬terized by intense worry.
Aphasia
Disturbance in language compre¬hension or production, often as a result of a stroke.
Apoptosis
Programmed cell death induced by specialized biochemical pathways, often serving a specific purpose in the development of an animal.
Arousal
A physiological state involving changes in the body and brain that motivate behavior and enable response to stimuli.
Astrocyte
A star-shaped glial cell in the cen¬tral nervous system that nourishes neurons; regulates the formation, maintenance, and pruning of synapses; and contributes to the blood-brain barrier.
Attention
A state of arousal in which the brain’s sensory processing is directed at a limited number of stimuli. Voluntary (en¬dogenous) attention is a conscious decision to focus on a particular stimulus. Involuntary (exogenous) attention is an unplanned focus on a change in the environment, such as a loud noise or sudden movement.
Auditory Nerve
A branch of the vestib¬ulocochlear nerve that transmits auditory information from the cochlea of the ear to the brain.
Autism Spectrum Disorder (ASD)
A set of conditions characterized, in part, by impaired social communication and inter¬action, and narrow, obsessive interests or repetitive behaviors.
Autonomic Nervous System
A part of the peripheral nervous system responsible for regulating the activity of internal organs. It includes the sympathetic and parasympa¬thetic nervous systems.
Axon
The fiber-like extension of a neuron by which it sends information to target cells.
Axon Terminal
The ends of axons where neurotransmitters are released to target cells.
Basal Ganglia
A group of interconnected structures located deep in the brain that play an important role in voluntary movement, motor skill learning, and habits. These struc¬tures include the caudate nucleus, putamen, nucleus accumbens, globus pallidus, and substantia nigra.
Benzodiazepines
A class of drugs that en¬hance activity of the brain’s primary inhibitory neurotransmitter, gamma-aminobutyric acid (GABA), to produce sedative and anti-anxiety effects. Benzodiazepines are often prescribed to treat anxiety disorders and insomnia.
Blood-Brain Barrier
A protective membrane composed of tightly packed endothelial cells lining the brain’s capillaries and highly special¬ized astrocytes, which controls the passage of certain molecules into and out of the brain.
Brain-Derived Neurotrophic Factor (BDNF)
A neurotrophic peptide that supports the growth and survival of neurons.
Brainstem
The major route by which the forebrain sends information to and receives information from the spinal cord and pe¬ripheral nerves. The brainstem includes the midbrain, pons, and medulla, and it controls, among other things, respiration and the regu¬lation of heart rhythms.
Broca’s Area
A region of the frontal lobe — usually the left hemisphere — that governs speech production.
Cell Body
Also called the soma, the part of a neuron that contains the nucleus (with DNA) and the organelles, but not the projections such as the axon or dendrites.
Central Nervous System
The brain and spinal cord.
Cerebellum
A large structure located at the roof of the hindbrain that helps to control the coordination of movement by making connec¬tions to the pons, medulla, spinal cord, and thalamus. It also may be involved in aspects of motor learning.
Cerebral Cortex
The wrinkled, outermost layer of the cerebrum consisting primarily of neuron cell bodies.
Cerebellum
A large structure located at the roof of the hindbrain that helps to control the coordination of movement by making connec¬tions to the pons, medulla, spinal cord, and thalamus. It also may be involved in aspects of motor learning.
Cerebral Cortex
The wrinkled, outermost layer of the cerebrum consisting primarily of neuron cell bodies.
Cerebrum
The largest part of the human brain associated with higher order function¬ing, such as thinking, perceiving, planning, and understanding language, as well as the control of voluntary behavior.
Circadian Rhythms
A cycle of behavior or physiological change lasting approximately 24 hours.
Cochlea
A snail-shaped, fluid-filled organ of the inner ear responsible for converting sound into electrical potentials to produce an auditory sensation.
Cognitive Behavioral Therapy
A form of counseling used to identify and change negative thought patterns that can contribute to anxiety and mood disorders.
Cones
A primary receptor cell for vision lo¬cated in the retina. It is sensitive to color and is used primarily for daytime vision.
Corpus Callosum
The large bundle of nerve fibers linking the left and right cerebral hemispheres.
Cortisol
A hormone manufactured by the ad¬renal cortex. In humans, cortisol is secreted in the greatest quantities before dawn, readying the body for the activities of the coming day.
Cranial Nerves
Twelve pairs of nerves that can be seen on the bottom surface of the brain. Some of these nerves transmit sensory infor¬mation; some control the movement of face, head, and neck muscles; others transmit infor¬mation to internal organs to regulate functions such as blood pressure and heart rate.
Critical Period
A period of heightened plasticity in brain development when certain experiences and sensory inputs are required for the formation of functional brain circuits.
Declarative Memory
Also called explicit memory, a type of memory that can be con¬sciously retrieved. It includes memory of facts (semantic memory) and memory of personal experiences (episodic memory).
Default Mode Network
A collection of brain regions activated during quiet rest.
Dementia
A decline in cognitive ability that interferes with day-to-day functioning.
Dendrite
A treelike extension of the neuron cell body. The dendrite is the primary site for receiving and integrating information from other neurons.
Depolarization
A change in a neuron’s membrane potential in which the cytoplasm becomes more positively charged. Neurons must depolarize beyond a certain threshold to generate an action potential.
Depression
A psychiatric disorder character¬ized by sadness, hopelessness, pessimism, loss of interest in life, reduced emotional well-being, and abnormalities in sleep, appetite, and energy level.
Dopamine
A catecholamine neurotransmit¬ter present in three circuits of the brain: one that regulates movement; a second, thought to be important for cognition and emotion; and a third that regulates the endocrine system. Deficits of dopamine in the motor circuit are associated with Parkinson’s disease. Abnormal¬ities in the second circuit have been implicat¬ed in schizophrenia.
Down Syndrome
A condition that results from the presence of an extra copy of chromo¬some 21. This genetic anomaly is associated with physical and developmental characteris¬tics, including mild to moderate intellectual disabilities; low muscle tone; and an increased risk of congenital heart defects, respiratory problems, and digestive tract obstruction.
