The Neuroscience on the Web Series:
Glossary of Neuroscience Terms C-E


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C

catastrophic reaction:
crying, screaming and yelling, etc. by  a person with Broca's aphasia as an expression of low frustration tolerance/awareness of their errors
 
cauda equina:
The continuation of nerve fibers in the part of the vertebral column that lies below the spinal cord; cauda equina is Latin for "horse's tail"
 
caudal:
"toward the tail," may mean the same as inferior; an antonym is rostral
 
caudate nucleus:
one of the two structures that make up the basal ganglia; it is divided into a head, body, and tail and is bounded on one side by the lateral ventricle
 
central canal:
the space in the middle of the grey matter of the spinal cord; it contains cerebrospinal fluid
 
central sulcus (fissure of Rolando):
the deep sulcus that separates the frontal and parietal lobes
 
cephalic:
a synonym of superior; refers to the upper parts of the nervous system
 
cerebellar peduncles:
three pairs of fiber bundles (the superior cerebellar peduncle, the middle cerebellar peduncle, and the inferior cerebellar peduncle) which connect the cerebellum to the brain stem; information passes on these tracts in both directions, every message that is sent or received by the cerebellum travels on the cerebellar peduncles
 
cerebellar dysarthria (ataxic dysarthria):
a disorder that results in jerky, uncoordinated movements of the speech musculature; it is caused by lesions in the cerebellum
 
cerebellum:
It is involved in the coordination and production of speech, the organization of muscle movement, coordination of fine motor movement, and balance; it is the center of a feedback loop involving motor and sensory information; "cerebellum" means "little brain" in Latin
 
cerebral dementia:
may result from anterior cerebral artery blockages. Confused language, or a language indicative of cognitive impairment, may also occur.
 
cerebral peduncles:
fiber bundles that are located in the brain stem; the cerebral peduncles connect the pons to the cerebrum
 
cerebral vascular accident:
is a temporary or permanent loss of functioning of brain tissue caused by an interruption in the cerebral blood supply
 
cerebrospinal fluid:
a clear liquid produced and found in the ventricles. It flows through the subarachnoid space (surrounding the brain and spinal cord), and inside the central canal of the spinal cord; it functions as a protective cushion for, brings nutrients to, and removes waste from, the neuraxis
 
cerebrovascular resistance:
makes it more difficult for blood to flow from one area to another. It can be caused by arterial spasm, a high level of tri-glycerides in the blood which increases its viscosity, or by elevated levels of cerebral spinal fluid.
 
cholesterol:
HDLs or high density lipoproteins are the "good" cholesterol. LDLs or low density lipoproteins are the "bad" cholesterol. It is all right to have high levels of HDLs, but a high concentration of LDLs is a health risk. Overall cholesterol levels should be under 200.
 
choroid plexes:
structures that produce cerebrospinal fluid by allowing certain components of blood to enter the ventricles; formed by a fusing of the pia mater and the ependyma
 
cingulate gyrus:
a cortical area (a gyrus) considered to be a part of the limbic system; it is located immediately superior to the corpus callosum
 
Circle of Willis (Circulus Arteriosus):
the main arterial anastomatic trunk of the brain; the Circle of Willis is a point where the blood carried by the two internal carotids and the basilar system comes together and is subsequently redistributed by the anterior, middle, and posterior cerebral arteries
 
circumlocutions:
wordy and circuitous description of unrecalled terms. For example the patient may say "have one of them up there" when trying to explain he's had brain surgery.
 
claustrum:
a structure considered by some anatomists to be a part of the basal ganglia
 
Closed Head Injury (CHI):
brain injury resulting from coup-contra coup, acceleration or deceleration injury. Classified as severe, moderate, or mild based on the degree to which consciousness is impaired immediately after injury. According to Clifton (1989), severe head injury has been defined as coma for longer than six hours. Concussion defines mild head injury.
Secondary damage in CHI includes widespread or localized edema as well as slowly developing hemorrhages (Ylvisaker and Szekeres, 1994, in Chapey, 1994).
 
cocktail hour speech:
often seen in a person with Wernicke's Aphasia
 
cognitive approach:
introduced by Schuell with the use of auditory stimuli, evolved through Duffy to use a multi-modality approach and by Chapey (1994) to use divergent thinking
 
collateral circulation:
a safety mechanism of the arterial system of the brain; collateral circulation involves the redirecting of blood through a route that is different than normal; it can be crucial when blockages occur
 
commissural fibers:
nerve fibers that connect the hemispheres of the brain; the corpus callosum, anterior commissure, and the posterior commissure are composed of commissural fibers
 
commissurectomy:
an operation that severs the corpus callosum; commissurectomies have been used as a treatment for severe epileptic seizures
 
completed stroke:
type most commonly seen, the infarction of brain tissue has ceased to occur
 
conduction aphasia:
a type of aphasia that may be the result of a lesion to the arcuate fasciculus
may result from anterior cerebral artery blockages
 
conduit d'approche:
(Goodglass and Kaplan, 1983) patient is aware of his/her paraphrasitic errors and will produce repeated approximations of the intended word, as if he is trying to untangle it
 
confrontation naming:
one way of testing one's word finding ability
 
confused language:
a language indicative of cognitive impairment that may occur as a result of anterior cerebral artery blockages and may accompanied by cerebral dementia, seems to be the result of cognitive problems with right hemisphere lesions.
 
contralateral hyposthesia:
lack of sensation on side of body opposite to site of lesion
 
contralateral innervation:
when a cranial nerve, or a portion of it, receives information only from fibers on the opposite side of the brain
 
conus medularis:
the point at which the spinal cord ends, just above the small of the back
 
convolution:
the corrogated appearance of the cortex, includes both gyri and sulci
 
coronal cut:
a cut that separates the brain into front and back portions; a cut that runs from ear to ear
 
corpora quadrigemina:
consists of the tectum and the four colliculi which are bumps on the tectum (two superior colliculi and two inferior colliculi); the corpora quadrigemina is located on the posterior surface of the midbrain
 
corpus callosum:
Latin for "large body," the corpus callosum is the major group of commissural fibers; it is located some distance down inside the longitudinal cerebral fissure; it connects the hemispheres and mainly connects mirror image sites
 
corpus striatum:
the group of structures that includes the basal ganglia and internal capsule; it is called the "striped body" because the internal capsule runs between the caudate nucleus and lenticular nucleus of the basal ganglia, creating a striped appearance
 
cortex:
the layer of cells that cover the two hemispheres of the brain; its surface is composed of gyri and sulci
 
cortical blindness:
caused by damage to occipital lobes, often when blood is cut off in the posterior cerebral arteries.
 
corticobulbar tract:
the fibers of the pyramidal tract that synapse with the cranial nerves located in the brain stem
 
corticopontine tract:
fibers from the motor strip of the cortex
 
corticopontocerebellar tract:
a fiber tract that brings a copy of the motor information (including information about the nature, destination, strength, and speed of the motor impulse being sent by the precentral gyrus) to the cerebellum from the frontal lobe; the information travels on this tract from the precentral gyrus, descending in the internal capsule, then synapsing with cells in the pons;  pontine nuclei then send second order neurons to the cerebellum on the middle cerebellar peduncle
 
corticospinal tract:
the fibers of the pyramidal tract that synapse with spinal nerves; these fibers carry information about voluntary movement to the skeletal muscles; as they descend they form part of the posterior limb of the internal capsule
 
coup contre-coup:
usually due to a fall or a blow to the head. The coup is the damage to the braim just beneath the site of impact. Contra-coup is the damage to the opposite side of the brain as the brain bounces against the skull.
 
cranial:
a synonym of superior; cranial refers to the upper parts of the nervous system
 
cricopharyngus m. or pharyngeal-esophageal (P.E) segment:
separates the pharynx from the esophagus. At the end of the pharyngeal stage of the swallow, it must relax to allow the bolus to enter the esophagus. (It is normally closed to prevent the reflux of food and to keep air out of the digestive system.) 

D

deep nuclei of the cerebellum:
four different nuclei (the dentate nucleus, the emboliform nucleus, the globose nucleus, and the fastigial nucleus) located deep within each cerebellar hemisphere that have axons to the brain stem and thus send messages out to be conveyed to other parts of the central nervous system; these nuclei are regulated by Purkinje cells which perform an inhibitory function.
 
Dementia:
Between 30 and 40 percent of Parkinson's patients suffer from dementia; loss of mental acuity
 
dendrite:
the part of the neuron that receives messages from the axons of other nerve cells; the two types of dendrites are apical dendrites and basilar dendrites
 
descending reticular formation:
the component of the reticular formation that is involved in autonomic nervous system activity; it receives information from the thalamus; the descending reticular formation also plays a role in motor movement
 
diabetes insipidus:
the most serious type of diabetes; diabetes insipidus is caused by lesions in the hypothalamus or between the pituitary gland and the hypothalamus
 
diachisis:
is a kind of post-lesional cerebral shock resulting in sudden inhibition of function diminishment and possibly a complete loss of functioning in brain areas distal to the site of lesion, may be far away from the point of original damage,   usually connected to the infarcted area by nerve pathways (Steadman, 1997). Cause of diachisis in unknown; it may be the result of edema, reduced cerebral blood flow, the release of neurochemicals or other factors which have not yet been identified. Diachisis can occur after CHI as well as after stroke.
 
diencephalon:
the thalamus and hypothalamus
 
Diffuse Brain Injury:
wide spread injury, it can impair attention and perception causing problems like neglect and prosopagnosia. An inability to analyze and synthesize information and a reduction in the rate of information processing may also result from wide-spread brain damage. In addition, long term memory and problem solving may be impaired. Reasoning, both inductive and deductive, may be involved. Convergent and divergent thinking are the two main parameters of reasoning. Convergent thinking often produces single conclusions while divergent thinking is open ended e.g. how many things can you do with a toothbrush? Pragmatic problems like impaired social judgment, reduced inhibition, and poor comprehension of abstraction may occur as well.
 
direct pyramidal tract (ventral pyramidal tract, anterior corticospinal tract):
the uncrossed (direct) fibers of the corticospinal tract that synapse with the spinal nerves on the ipsilateral side of the body; these fibers travel down the ventral aspect of the cord
 
diskinesias:
disorders of involuntary movement; may be the result of extrapyramidal tract lesions
 
divergent thinking:
a patient with aphasia is required to produce several creative responses to every stimulus. For example, the patient might be asked to think of several unusual ways to make use of an everyday object.
 
dopamine:
a neurotransmitter involved in the inhibitory function of the basal ganglia; it is produced by the substantia nigra. Lack of dopamine can result in Parkinson's disease.
 
dorsospinocerebellar tract:
one of the two main tracts that bring sensory information from the periphery to the cerebellum; proprioceptive information from the upper body travels on this fiber tract; it carries messages received by the reticular nuclei in various parts of the brain stem from the cortex, spinal cord, vestibular system and red nucleus; information from this tract enters the cerebellum on the inferior cerebellar peduncle
 
dura mater:
Latin for "hard mother," the dura mater is the most superior of the layers of the meninges; this tough, inflexible tissue forms several structures that serve to separate the cranial cavity into compartments and protect the brain from displacement, as well as forming several vein-like sinuses that carry blood back to the heart
 
dysarthria:
According to Darley, Aronson and Brown (1975), a speech disorder resulting from a weakness, paralysis, or incoordination of the speech musculature that is of neurological etiology. All types of dysarthria  result from damage to the central or peripheral nervous system that impairs the transmission of neural messages to the muscles involved in speech. In contrast to apraxia which affects the brain's capacity to produce the "programs" necessary for coordinated motor movements, dysarthria results from an inability to send the proper messages to the musculature. While apraxia affects articulation and, to some extent, prosody, dysarthria can impair all processes involved in speech production including respiration, phonation, articulation, resonance and prosody. Based on etiology, Darley, Aronson and Brown (1969), identified six different types of dysarthria. These include four forms of the disorder which are caused by damage to upper motor neurons. They include spastic, hyperkinetic, hypokinetic, and ataxic dysarthria.
 
dysphagia:
difficulty swallowing, types can include the most common type, delayed/absent initiation of the pharyngeal stage of the swallow, disorders of the pharyngeal stage of the swallow  which are the most prevalent type of dysphagia among the CVA population, and types associated with site of lesion including brain stem stroke, subcortical stroke, unilateral left hemisphere stroke, Unilateral Right Hemisphere Stroke, and multiple strokes. Therapy strategies may include Icing, Thermal Stimulation, Sensory Stimulation, Suck-Swallow technique, Chewing, Oral-motor exercises. Posture to facilitate swallow is also utilized for therapy, as is selection of food consistencies and techniques for protecting the airway
 
Dystonia:
causes slow jerky movements which are most likely to occur in the trunk, neck and proximal parts of the limbs.

E

Edema:
swelling, begins two or three days after a cerebral insult. Only in the area that has been injured, however, as localized swelling can greatly increase pressure throughout the whole cranium, the functioning of the entire brain may be affected. Edema of the brain should begin to decrease by the beginning of the first week post-injury. As intracranial pressure returns to normal levels, any behavioral changes that were caused by the swelling rather than by the brain injury will disappear.
 
efferent fibers:
nerve fibers that take messages from the brain to the peripheral nervous system; motor fibers are efferent
 
Effortful Swallow:
increases the tongue driving force by causing exaggerated retraction of the tongue. This helps to get food past the valleculae. The patient is directed to squeeze hard with hi/her   throat and neck muscles during the swallow.
*** The above techniques are most often used with patients who have had brain stem lesions and so have severe dysphagia, but still have good cognitive ability.
 
endolymph:
the fluid that fills the semicircular canals of the inner ear
 
ependyma:
the membranous lining of the ventricles
 
Epidural Bleeding:
According to Stedman (1997) epidural hemorrhaging, also called extra dural, is an accumulation of blood between the skull and the dura mater. It is usually the result of acceleration-deceleration trauma. This type of bleeding results from lesions of the arteries, most commonly the middle meningeal artery.  The patient is usually unconscious immediately, then lucid briefly, then loses conscious again from a large clot in the epidural space. The clot may compress cranial nerves resulting in pupillary dilation, as well as ipsalateral weakness or paralysis (Pires,1984, in Urosovich, 1984).
 
Surgical aspiration of hematomas resulting from epidural bleeding may be used as a life-saving technique.
 
epidural space:
a potential space between the dura mater and the skull
 
esophageal stage of the swallow:
involuntary stage where the larynx returns to its normal position, and the cricopharyngus muscle contracts to prevent reflux and respiration resumes.
 
executive function:
according to Dunkla, 1996, the executive function regulates and directs cognitive processes. It organizes behavior, sets goals, and facilitates goal achievement while inhibiting behavior detrimental to goal completion.
 
expressive Aphasia:
most commonly called  Broca's Aphasia, also called Motor Aphasia
 
external carotid artery:
a division of the common carotid; the external carotid supplies blood to the face
 
external granular layer:
the second most superior layer of the cortex; it is very dense and contains small granular cells and small pyramidal cells
 
external circular layer (of the pharynx):
made up of the superior, middle, and inferior pharyngeal constrictor muscles
 
external pyramidal layer (medial pyramidal layer):
the third most superior layer of the cortex; it contains pyramidal cells in row formation and the cell bodies of some association fibers
 
extraneural factors:
factors that may include abnormal blood pressure, cerebrovascular resistance, and arteriosclerosis may impede collateral circulation
 
extrapyramidal tract:
involved in automatic motor movements, gross motor movements, posture and muscle tone (in combination with the autonomic nervous system) and facial expression; it is an indirect, multisynaptic tract; the components of the extrapyramidal system include the basal ganglia, the red nucleus, substancia nigra, the reticular formation, and the cerebellum, consists of neurons that regulate involuntary/automatic movements. Lesions in the extrapyramidal tract cause various types of diskinesias or disorders of involuntary movement. The problems mostly commonly affecting the extrapyramidal tract include degenerative diseases, encephalitis, and tumors.