neural networks
interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results. Computer simulations of neural networks show analogous learning.
endocrine system
the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream
hormones
chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another
adrenal glands
a pair of endocrine glands just above the kidneys. the adrenals secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress.
pituitary gland
the endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands
electroencephalogram
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.
PET scan
a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
MRI
a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain
fMRI
A technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans.
brainstem
The oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions
medulla
the base of the brainstem; controls heartbeat and breathing
reticular formation
a nerve network in the brainstem that plays an important role in controlling arousal
thalamus
the brain's sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla
cerebellum
the "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance
limbic system
a doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres; associated with emotions such as fear and aggression and drives such as those for food and sex. Includes the hippocampus, amygdala, and hypothalamus.
amygdala
two lima bean-sized neural clusters that are components of the limbic system and are linked to emotion
hypothalamus
a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion
cerebral cortex
the intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control and information-processing center
glial cells
cells in the nervous system that support, nourish, and protect neurons.
frontal lobes
the portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements
parietal lobes
The portion of the cerebral cortex lying at the top of the head and toward the rear; includes the sensory cortex
occupital lobes
part of the cerebral hemisphere that receives and interprets visual information
temporal lobes
the portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each of which receives auditory information primarily from the opposite ear
motor cortex
an area at the rear of the frontal lobes that controls voluntary movements
sensory cortex
the area at the front of the parietal lobes that registers and processes body touch and movement sensations
association areas
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
aphasia
impairment of language, usually caused by left hemisphere damage either to Broca's area (impairing speaking) or to wernicke's area (impairing understanding)
broca's area
controls language expression-an aread of the frontal, usually in the left hemisphere, that directs the muscle movements involved in speech
wernicke's area
controls language reception-a brain area involved in language comprehension and expression;usually in the left temporal lobe
plasticity
the brain's capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development
corpus callosum
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them
split brain
a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them