Glossary

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Cerebral hemispheres: The two halves of the cerebrum that comprise the cerebral cortex, the underlying white matter, and the basal ganglia. Each hemisphere primarily controls the sensory input and motor functions of the opposite half of the body.

Cerebrospinal fluid (CSF):
The clear fluid that fills the cavities (i.e., ventri cles) within the brain and that sur rounds the brain and spinal cord.

Cerebrum:
The largest portion of the brain; includes the cerebral hemi spheres.
Compound: In chemistry, a substance composed of two or more different elements that are chemically combined.

Corpus callosum:
The tract of nerve fibers connecting the two cerebral hemispheres.

Cortex:
The outer layer of an organ.
Dementia: A condition of global intellec tual impairment, including the loss of abstract thinking and memory, person ality changes, breakdown of social skills, and other disturbances of higher cognitive functioning.

Dendrite:
The branched projections of a neuron that receive nerve impulses from other cells. Most neurons have more than one dendrite.

Diencephalon:
The area of the brain located beneath the cerebral cortex consisting of the thalamus and the hypothalamus.

Element:
A substance composed of only one kind of atom.

Frontal lobes:
The anterior region of the cerebrum.
Gray matter: Brain tissue composed mostly of dendrites and cell bodies that makes up the outer surface of the cerebral cortex as well as portions of the brain at the base of the cerebral hemispheres.

Gyrus (Gyri):
The ridges of rounded, convoluted brain tissue that forms the cerebral hemispheres.
Hippocampus: A region of the temporal lobe that is thought to play a role in learning and memory as well as in alcohol withdrawal seizures.
Histology: The science of the detailed structure of cells, tissues, and organs in relation to their function.
Hypothalamus: An important part of the limbic system with many regula tory functions, including the control of motivation and emotional behavior. The hypothalamus is located in the diencephalon.
Inferior: In anatomy, situated nearer to the bottom (i.e., in humans, toward the soles of the feet).
Isotope: An isotope is one of two or more atoms that have the same number of protons (i.e., are chemically identi cal) but have different numbers of neutrons.
Korsakoff's syndrome: An organic brain syndrome associated with prolonged, heavy ingestion of alcohol, character ized by anterograde amnesia. Also see WernickeKorsakoff syndrome (WKS).

Lenticular (lentiform) nuclei:
Part of the basal ganglia comprising the putamen and the globus pallidus. Two sets of lenticular nuclei exist, one in each hemisphere of the brain.
Magnetic field: A physical field that arises from an electric charge in mo tion or from a magnet, producing a force that attracts particles of specific elements.
Mammillary body: A paired brain struc ture located near the hypothalamus that is involved in memory and in the control of autonomic (i.e., involuntary) body functions.

Morphology:
The biological study of the form and structure of organisms.

Nucleus:
The center structure of a cell or of an atom.
Neuron: A nerve cell, which is made up of a cell body, an axon, and one or more dendrites.
Neurotransmitter: A chemical messen ger released by a neuron to carry a signal to adjacent neurons.

Occipital lobe:
The part of the cerebrum at the rear of each hemisphere, sepa rated from the parietal lobe by the parietooccipital sulcus; the surface of the occipital lobe is involved in vision.

Orbitofrontal cortex:
The part of the cerebral cortex covering the base of the frontal lobes.

Parietal lobe (region):
The region of the cerebral cortex, located in the middle part of the cerebral hemispheres, that mainly receives information not from the sensory organs but from receptors in or near the body surface. It is sepa rated from the occipital lobe by the parietooccipital sulcus.
Posterior: Toward the rear of the body.

Prefrontal cortex:
The most anterior section of the frontal cortex; involved in memory processes, specifically in delayed response tasks.
Radio wave: An electromagnetic wave having a frequency between approxi mately 10 kilohertz and 300,000 megahertz; a key component of imaging technology.
Radioisotope: An isotope that changes to a more stable state by emitting parti cles (i.e., radiation) from its nucleus.
Receptor: A structure in the wall or interior of a nerve cell or other cell that recognizes and binds to neuro transmitters and other chemical messengers.

Sulci (Sulcus):
The grooves or furrows on the surface of the brain.

Superior:
In anatomy, situated nearer to the top of the head.
Sylvian fissure: The deepest and most prominent of the fissures in the cere bral cortex.
Temporal lobe: The region of the cere bral cortex forming part of the sides and bottom of the brain on each side. This region is involved in sensory processing, language functions, and emotions.

Thalamus:
The graymatter structure that forms part of the diencephalon, the brain's relay center to the cerebral cortex.
Thiamine: Vitamin B 1 ; a deficiency in this vitamin has been linked to Korsakoff's syndrome.

Tomography:
The technology of making an image of thin slices of tissue within the body.
Ventricles: A normal cavity (e.g., in the brain or heart). In the brain, the ventri cles are filled with cerebrospinal fluid.
Vermis: The structure located between the two halves of the cerebellum that is important for controlling particular motor functions.

WernickeKorsakoff syndrome (WKS):
A neurological disorder thought to be caused by thiamine deficiency. WKS is characterized by impairments in memory (e.g., anterograde amne sia) as well as deficits in abstraction and problemsolving. Wernicke's encephalopathy is an acute condition characterized by general confusion and incoherent speech. It may or may not precede Korsakoff's syndrome.
White matter: Brain tissue composed mainly of axons.