-
Absolute refractory period
- The brief time interval following an action
- potential when a neuron is incapable of being stimulated to fire another
- impulse
-
Acetylcholine
- An excitatory neurotransmitter that operates at
- synapses with muscles and is also the transmitter in some neural networks
- involved in memory
-
Action potential
- A nerve impulse resulting from the
- depolarization of an axon’s cell membrane
-
Adrenal gland
- Endocrine glands that release stress hormones, including
- catecholamine and corticosteroids
-
Agonist
- A drug that increases or mimics the activity of
- a neurotransmitter
-
All or none law
- state that an action potential is not
- proportional to the intensity of simulation; either a neuron fires with maximum
- intensity or it does not fire (compared with graded potential)
-
Amygdala
- A limbic system structure that helps organize emotional
- response patterns
-
Antagonist
- A drug that inhibits or decreases the action of
- a neurotransmitter
-
Aphasia
- The partial or total loss of ability to understand speech
- (receptive aphasia) or to produce it (productive aphasia)
-
Association cortex
- The area of the cerebral cortex that do not have
- sensory or motor functions but are involved in the integration of neural
- activity that underlies perception, language, and other higher-ordeal mental
- processes
-
Autonomic nervous system
- The branch of the peripheral nervous system that activates
- the body’s involuntary muscles (e.g., heart) and internal organs
-
Axon
- An extension from one side of the neuron cell body that conducts
- nerve impulses to other neurons, muscles, or glands
-
Brain stem
- The portion of the brain formed by the swelling of the
- spinal cord as it enters the skull; its structures regulate basic survival
- functions of the body, such as heart rate and respiration
-
Broca’s area
- A region of the left frontal lobe involved in
- speech production
-
Central nervous system
- The portion of the nervous system that includes
- the brain and the spinal cord
-
Cerebellum
- A convoluted hindbrain structure involved in motor
- coordination and some aspects of learning and memory
-
Cerebral cortex
- The gray, convoluted outer covering of the brain that is the
- seat of higher-order sensory, motor, perceptual, and mental processes
-
Cerebrum
- The most advanced part of the brain, containing the cerebral
- cortex and underlying structures
-
Computerized axial tomography (CT or CAT) scan
- scan-A method of scanning the brain with narrow
- beams of x rays that are then analyzed and combined by a computer to provide
- pictures of brain structures from many different angles
-
Corpus callosum
- A broad brand of white, myelinated fibers that connects the
- left and right cerebral hemispheres and allows the two hemispheres to
- communicate with one another
-
Dendrites
- small branching fibers that extend from the soma of a neuron
- and receive messages from adjacent neurons
-
Electroencephalograph
- A device used to record the simultaneous
- activity of many thousands of neurons through electrodes attached to the scalp
-
Endocrine system
- The body’s system of glands that secrete hormones into the
- bloodstream and thereby affect many bodily functions
-
Forebrain
- Brain structure above the midbrain, including
- the thalamus, hypothalamus, limbic system, and the cerebral hemispheres;
- involved in higher-order sensory, motor, and cognitive functions
-
Functional MRI
- A brain scanning procedure that produces pictures of blood
- flow in the brain taken less than a second apart
-
Graded potentials
- A change in the electrical potential of a neuron that is
- proportional to the intensity of the incoming stimulation but not sufficient to
- produce an action potential
-
Hindbrain
- The part of the brain situated immediately above the spinal
- cord that contains the brain stem and cerebellum
-
Hippocampus
- A structure of the limbic system that plays a key role in
- the formation and storage of memories
-
Homeostasis
- the maintenance of biological equilibrium, or balance,
- within the body
-
Hormones
- Chemical substances secreted by the glands of the endocrine
- system that travels in the bloodstream and affect bodily organs, psychological
- functions, and development
-
Hypothalamus
- A forebrain structure located below the thalamus and above
- the pituitary gland that controls autonomic and hormonal processes and plays a
- major role in many aspects of motivation and emotional behavior
-
Interneurons
- Neurons that are neither sensory nor motor neurons but that
- perform associative or integrative function within the nervous system
-
Lateralization
- The degree of localization of a function in
- either the right or the left cerebral hemisphere
-
Limbic system
- A group of subcortical structures, including the hippocampus
- and amygdala, which are involved in organizing many goal-directed and emotional
- behaviors
-
Magnetic resonance imaging
- A brain scanning procedure that produces a
- highly detailed image of living tissue based on the tissue’s response to a
- magnetic field; can be used to study both structure and, in the case of
- functional MRI (fMRI), brain functions as they occur
-
Medulla
- A brain stem structure that controls vital functions,
- including heartbeat and respiration
-
Midbrain
- Brain structure above the hindbrain that are involved in
- sensory and motor functions and in attention and states of consciousness
-
Motor cortex
- The cortical area in the rear portion of the frontal lobes
- that controls voluntary movements on the opposite sides of the body
-
Motor neurons
- specialized neurons that carry neural messages from the
- brain and spinal cord to the muscles and glands
-
Myelin sheath
- A fatty insulating substance on the axon of some neurons
- that increase the speed of neural transmission
-
Neural plasticity
- The ability of neurons to modify their structure and
- function in response to experiential factors or injury
-
Neural stem cell
- Immature “uncommitted” cells that can mature into any type
- of neuron or glial cell needed by the brain
-
Neurogenesis
- The production of new neurons in the nervous
- system, sometimes to replace neurons that have died or been damaged
-
Neuromodulators
- neurotransmitter substances that are released by
- neurons and circulate within the nervous system to affect the sensitivity of
- many neurons to their natural transmitter substances
-
Neurons
- Nerve cells that constitute the basic building block of the
- nervous system
-
Neurotransmitters
- Chemical substances that are released from the
- axon of one neuron, travel across the synaptic space, and bind to specially
- keyed receptors in another neuron, where they produce a chemical reaction that
- is either excitatory or inhibitory
-
Parasympathetic nervous system
- The branch of the autonomic nervous system that slows down
- bodily processes to conserve energy and reduce arousal
-
Peripheral nervous system
- All of the neurons that connect the central
- nervous system with the sensory receptors, the muscles, and the glands
-
Pons
- A brain stem structure having sensory and motor tracts whose
- functions are involved in sleep and dreaming
-
Positron emission tomography scan
- A procedure that provides a visual display of
- the absorption of a radioactive substance by neurons, indicating how actively
- they are involved as the brain performs a task
-
Prefrontal cortex
- The area of the frontal lobe just behind the eyes and
- forehead that is involved in the executive functions of planning,
- self-awareness, and responsibility
-
Psychoactive drugs
- Chemicals that produce alternations in
- consciousness, emotion, and behavior
-
Receptor sites
- protein molecules on neurons’ dendrites or soma that are
- specially shaped to accommodate a specific neurotransmitter molecule
-
Resting potentials
- the voltage differential between the inside and outside of a
- neuron (above-70mv) caused by the unequal distribution of ions inside the
- neuron’s membrane and outside in the fluid surrounding the neurons when the
- neuron is at rest
-
Reticular formation
- -A structure extending from hindbrain into the lower
- forebrain that plays a central role in consciousness, sleep and attention, in
- part by alerting higher brain centers (ascending portion) and by selectively
- blocking some inputs to higher regions in the brain (descending portion)
-
Reuptake
- The process whereby transmitter substances are
- taken back into the presynaptic neuron so that they do not continue to
- stimulate postsynaptic neurons
-
Sensory neurons
- specialized neurons that carry messages from the sense
- organs to the spinal cord and brain
-
Somatic nervous system
- The branch of the peripheral nervous system that
- provides inputs from the sensory receptors and outputs to the voluntary muscles
- of the body
-
Somatic sensory cortex
- Cortical strips in the front portions of the
- parietal lobes that receive sensory inputs from the opposite side of the body
-
Sympathetic nervous system
- The branch of the automatic nervous system that
- has an arousal function on the bodily processes and mobilizing the body
-
Synaptic space
- The microscopic space between the axons of one
- neuron and the dendrites or cell body of another over which the nerve impulse
- transmitted v
-
Synaptic vesicles
- Chambers within the axon that contains the
- neurotransmitter substance
-
Thalamus
- A major sensory integration and relay center in
- the forebrain, sometimes referred to as the brain’s sensory switchboard
-
Wernicke’s area
- An area of the left temporal lobe that is
- involved in the speech comprehension
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