a nerve cell; the basic building block of the nervous system.

neurons that carry incoming information from the sensory receptors to the brain and spinal cord.

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.

neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs.

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands.

a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

a neural impulse; a brief electrical charge that travels down an axon

the level of stimulation required to trigger a neural impulse.

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron.

chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, they travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

a neurotransmitter’s reabsorption by the sending neuron.

“morphine within”--natural, opiatelike neurotransmitters linked to pain control and to pleasure.

the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems

the brain and spinal cord.

the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body

bundled axons that form neural “cables” connecting the central nervous system with muscles, glands, and sense organs.

the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system.

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.

the division of the autonomic nervous system that calms the body, conserving its energy.

a simple, automatic response to a sensory stimulus, such as the knee-jerk response.

the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.

a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

the endocrine system’s most influential gland. Under the influence of the hypothalamus, it regulates growth and controls other endocrine glands.

tissue destruction. In the brain, it is a naturally or experimentally caused destruction of brain tissue.

an amplified recording of the waves of electrical activity that sweep across the brain’s surface. These waves are measured by electrodes placed on the scalp.

a visual display on brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. It scans show brain anatomy.

a technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. These scans show brain function.

the oldest part and central core of the brain, beginning where the spinal cords swells as it enters the skull; it is responsible for automatic survival functions.

the base of the brainstem; controls heartbeat and breathing

a nerve network in the brainstem that plays an important role in controlling arousal.

the brain's sensory switchboard, located on top of the brainstem;; it directly messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.

the “little brain” at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance.

neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives.

two lima bean-sized neural clusters in the limbic system; linked to emotion

a neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward

the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.

cells in the nervous system that support, nourish, and protect neurons.

portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements.

portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position.

portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual friends.

portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.

an area at the rear of the frontal lobes that controls voluntary movements.

an area at the front of the parietal lobes that registers and processes body touch and movement sensations.

areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.

the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

the formation of new neurons

the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.