Descriptionary

cortex the outer surface and folds of the cerebrum. cranium the top of the skull.

delta waves the high-voltage brain waves that pre­dominate when someone is asleep.

dorsolateral prefrontal cortex a portion of the pre- frontal cortex involved in reading and concentration.

dura mater the outer covering of the brain.

dysphasia difficulty in speaking or understanding speech, due to a brain condition.

electroencephalogram otherwise known as an EEG, a graphical recording of the electrical activity of the brain.

electroencephalograph the machine that records the electrical activity of the brain.

encephalitis inflammation of the brain.

encephalomeningitis infection of the brain and dura mater.

encephalon the brain.

encephalosclerosis hardening of the brain.

epilepsy a brain condition characterized by electri­cal disturbances that cause seizures and loss of con­sciousness.

forebrain the front portion of the brain, the latest to evolve, after the midbrain and the hindbrain.

frontal lobe the left and right lobes, located at the front of the cortex, in front of the forehead, the center of reasoning, judgment, and planning. Damage to this area, through blows to the head or illness, may cause frontal lobe syndrome, a mental disorder character­ized by short attention span, tactless or insensitive behavior, impulsiveness, and criminal behavior.

fusiform gyrus a fold or convolution in the tempo­ral lobe, active in face recognition.

Geschwind's territory in the parietal lobe of the cortex, a region that connects Broca's region with Wernicke's area and is thought to be involved in childhood language acquisition.

gray matter the gray or darker portions of the brain containing concentrated neuron cells and including the cerebral cortex, thalamus, basal ganglia, and the outer layer of the cerebellum. Gray matter is found in lower concentrations in people with bipolar disorder and schizophrenia, but it is unknown if it is the cause or the effect.

gyrus any one of the elevated convolutions at the surface of the cerebrum.

hemisphere the left or right division of the cere­brum.

Heschl's gyrus in the temporal lobe, a convolution involved in language and music processing.

hindbrain the oldest part of the brain, evolving before the midbrain and the forebrain, at the back of the head.

hippocampus in the limbic lobe, a seahorse-shaped area involved in the formation and storage of mem­ory, which is known to shrink beginning in middle age, causing, most notably, deficiencies in face-name associations. The hippocampus is also involved in triggering memories in response to smells.

hydrocephalus a postbirth condition characterized by fluid buildup around the brain, causing enlarge­ment of the skull.

hypothalamus located below the cerebrum, the part of the brain that regulates body temperature and blood pressure.

idiot savant syndrome injury to the left hemisphere of the brain before, during, or after birth, causing the right hemisphere to enlarge and overcompensate. The sufferer has below-average left-brain functioning while having superhuman right-brain functioning.

inferior temporal gyrus in the temporal lobe, a fold involved in the recognition of objects.

intraparietal sulcus in the parietal lobe, a sulcus involved with language and the spelling of words.

lateral temporal cortex part of the temporal lobe involved in rhyming words.

left caudate portion of the left hemisphere involved in the process of back-and-forth switching of lan­guage use in bilingual people.

left inferior parietal cortex portion of the inferior parietal cortex involved in remembering unfamiliar faces.

left prefrontal cortex portion of the prefrontal cor­tex involved in remembering unfamiliar faces.

limbic lobe in the cerebrum, a lobe along the cor­pus callosum that contains the hippocampus and the cingulate gyrus.

limbic system in the upper brain stem, the old or reptilian brain that regulates hunger, thirst, sex, fight­ing, and basic emotion.

lobe one of five sections of the cerebrum—the fron­tal, limbic, parietal, occipital, and temporal—roughly divided by deep folding.

medial prefrontal cortex portion of the prefrontal cortex involved in social memory.

medulla oblongata the base of the brain; it regu­lates respiration and circulation.

meningitis inflammation of the covering of the brain.

microencephalon an abnormally small brain.

midbrain the portion of the brain that evolved after the hindbrain but before the forebrain, at the center of the head.