The Neuroscience on the Web Series:
Glossary of Neuroscience Terms T-Z

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T

 
Tardive Dyskinesia:
a condition which results from long-term use of anti-psychotic drugs called phenothiazines
 
TBI: seeTraumatic Brain Injury
 
tectum:
the roof of the brain stem
 
telegraphic speech::
function words or grammatical morphemes, morphological inflections (e.g. plurals,past tense),articles, conjunctions and prepositions are omitted. In addition, nouns, verbs, adjectives and adverbs may be produced. Output can be restricted to noun-verb combinations. Sentence length is short. Average utterance length (MLU) is typically about 2. In extreme cases, the patient may only be able to produce single word utterances.
 
temporal lobe:
the lobe of the brain that is inferior to the lateral sulcus and anterior to the occipital lobe; it is associated with auditory processing and olfaction
 
temporal parietal lobe:
often a site of lesion for Wernicke's Aphasia (the angular gyrus may also be affected)
 
temporalis muscle of the oral cavity:
elevates, retracts, and assists in closing the mandible
 
TBI: Traumatic Brain Injury:
According to Adamovich, Henderson, and Auerbach (1984), as many as 400,000 head injuries occur in the United States each year. The severity of head injury has generally been classified as mild, moderate and severe. Mild head injury has been defined as concussion, while severe head injury means being in a coma for at least six hours. There does not appear to be a consensus for a definition of moderate head injury. Jennett and Teasdale developed the Glasgow Coma Scale in 1974 (Bach-y-Rita, 1989). It is a numerical scale that quantifies level of consciousness in response to three categories: response to pain, ability to open eyes, and ability to speak. 
 
tensor veli palitini (oral cavity):
tenses the velum. It receives innervation from the trigeminal (CN. V).
 
tentorium cerebelli:
formed by the dura mater, the tentorium cerebelli separates the cerebrum from the cerebellum
 
Tentorial Herniation
Due to the edema that follows CHI, brain matter can be forced through the tentorial notch. The notch is a cavity formed by the the tentorium cerebelli. The tentorium is a sheath of hard tissue, formed by the dura mater. According to FitzGerald (1997), it forms a tent above the posterior fossa. It separates the cerebrum and brain stem from the cerebellum. Tentorial herniation may cause decortication or removal of cortical tissue from the underlying white matter. It may also put excessive pressure on the brain stem and thus affect cranial nerves involved in vital functions including respiration and circulation. Symptoms indicating that the brain stem is under too much pressure include sleepiness, bradycardia (slow heart rate), confusion, respiratory difficulties, and pupil dilation (due to pressure on the nuclei of CN III) (Bach-y-Rita, 1989).After CHI, barbiturate induced coma may be used to manage intracranial pressure.
 
thalamic adhesion (massa intermedia):
the tissue that connects the two thalamic bodies of the thalamus
 
thalamus:
a subcortical structure that receives and integrates sensory information from the periphery (with the exception of smell), and sends the information to the cortex for further processing; the thalamus is composed of two thalamic bodies and the massa intermedia; it is located inferior to the caudate nucleus and the fornix and medial to the lenticular nucleus
 
third ventricle:
one of the four ventricles, it contains cerebrospinal fluid; it lies between the two thalamic bodies, with the massa intermedia passing through it and the hypothalamus forming its floor and part of its lateral walls
 
Thrombosis:
total blockage of an artery due to plaque build-up or emboli
 
TIA: see transient ischemic attack
 
Token Test (DeRenzi & Vignolo, 1966):
assesses subtle receptive language dysfunction. Can be used to evaluate the auditory comprehension of Broca's aphasics and helps to distinguish between Broca's aphasia and verbal apraxia. The test has five parts involving the manipulation of objects of different colors, shapes, and sizes and becomes progressively more difficult. It tests receptive language by by requiring the patient to follow instructions like "Put the red square on the yellow circle." However you must be aware that words like "before" which are grammatical morphemes may be missed due to conceptual or semantic problems. Also, limb apraxia may not allow the patient to carry out the instructions, even though he/she understands them.
 
topical disorientation:
the inability to know location and strategy to move about in an environment
 
transcortical aphasia:
a type of aphasia that may occur as the result of blockages in the water shed areas of the brain. Lesions are typically smaller than those that cause Broca's aphasia and are superior to and often anterior to Broca's area. Broca's area itself is not affected, but the damage may extend down into the white matter including the white matter below Broca's area. Luria (1966) referred to this syndrome as dynamic aphasia.

Communication between Broca's area and the pre-motor or supplementary motor area (Brodmann's Area 6) is cut off. Because Wernicke's area and the arcuate fasciculus are spared these patients have good repetition (Brookshire, 1997). This type of lesion may also sever links between Broca's area and basal ganglia and/or the thalamus, which may affect motor and pre-motor function.  In addition, the damage could cause symptoms by affecting the link between Broca's area and the limbic system which also seems to be involved in memory and speech and language.
 
Characteristics are: Repetition is much better than other types of speech. In repetition, grammar and articulation are normal. Articulation in general is fair to good. Little or no paraphasia is present. Confrontational naming is well-preserved. The patient will respond well to prompting with phonemic cues. Auditory comprehension is fair to excellent. According to Goodglass and Kaplan (1983) the fluent/nonfluent distinction is not especially applicable to this syndrome. Sometimes the patient will produce a grammatically correct, well-articulated sentence.
 
Transient Ischemic Attacks (TIAs):
transient disturbances of the blood supply to a localized part of the brain, which produce a temporary, focal lesion. Unlike strokes they resolve in spontaneous and complete recovery. Symptoms of TIAs mimic those of stroke.and severe TIAs cannot be differentiated from a stroke until recovery occurs. TIAs typically last between 2 and 15 minutes, although such an event could conceivably last as long as 24 hrs. It is also possible to have a series of many brief TIAs during one day. For example, a patient might have 10 or more transient ischemic attacks within a 24 hr. period.
 
transverse cut:
a cut that divides the brain into upper and lower sections; perpendicular to coronal, medial, and sagittal cuts
 
Trigeminal Nerve (Cranial Nerve V):
both a motor and sensory nerve, efferent  innervates the muscles involved in chewing. These include the temporalis, the masseter, the medial, and the lateral pterygoid, also innervates the tensor veli palatine muscle, which tenses the velum, in addition, the trigeminal assists the glossopharyngeal nerve in raising the larynx and pulling it forward during the laryngeal substage of the pharyngeal swallow. Sensory component sensation, except taste to the anterior 2/3 of the tongue and information from the face, mouth and mandible

U

 
uncinate fit:
an epileptic seizure that is preceded by an olfactory hallucination
 
upper motor neurons:
a type of first order neuron that carries motor impulses; the upper motor neurons remain inside the neuraxis', they synapse with lower motor neurons  

V

 
Vagus Nerve (Cranial Nerve X):
Motor Components include responsibility for raising the velum as it innervates the glossopalatine and the levator veli palatine muscles, along with CN. IX innervates the pharyngeal constrictor muscles, along with CN. XI innervates the intrinsic musculature of the larynx. It is responsible for vocal fold adduction during the swallow.
 
Also innervates the cricopharyngeus muscle. The vagus controls the muscles involved in the esophageal stage of the swallow as well as those that control respiration. (This is the only cranial nerve that influences structures inferior to the neck.)
 
Sensory Components include carrying information from the velum and posterior and inferior portions of the pharynx and mediation of sensation in the larynx.
 
valleculae:
space between the epiglottis and base of the tongue
 
velum:
five muscles which control the movements of the velum are :  palatoglossal and the levator veli palatini both raise the velum. They are innervated by the vagus nerve (CN. X). The tensor veli palatini tenses the velum. It receives innervation from the trigeminal (CN. V). The palatopharyngus depresses the velum and constricts the pharynx. It is innervated by the spinal accessory (CN. XI). The muscularis uvula shortens the velum. It is also innervated by the spinal accessory. Poor velopharyngeal closure will affect speech but is not a matter of great concern in regard to swallowing. Patients may be concerned about it and believe that it is very important. While the entrance of food into the nasopharynx may be unpleasant, it is certainly not life-threatening.
 
ventral:
toward the belly
 
ventricles:
four spaces within the brain that are filled with cerebrospinal fluid, they protect the brain by cushioning it and supporting its weight; they include the two lateral ventricles, the third ventricle, and the fourth ventricle
 
ventrospinocerebellar tract:
one of the two main tracts that bring sensory information from the periphery to the cerebellum; it is a fiber tract that contains proprioceptive fibers from the lower body; its axons decussate and travel upward on the contralateral side of the spinal cord, then cross again and continue upward ipsilaterally, the fibers then enter the cerebellum on the superior cerebellar peduncle
 
Verbal paraphasias:
paraphasias in which a word is substituted for the target word. (The substitution must be a real word. If it is not, the paraphasia is classified as neologistic.) Two types of verbal paraphasias: within category/semantic paraphasias and remote paraphasias. Within category errors involve the substitution of a word that is closely related to the target word, as in cat/dog. Remote errors involve the substitutions of a word that is only distantly related to the target word, as in sink/dog. Remote paraphasias are, of course, indicative of more severe language problems than are within category substitutions.
 
vermis:
"worm," a thin structure that separates the hemispheres of the cerebellum from one another
 
vertebral arteries:
one of the two main branches of the subclavian arteries; the two vertebral arteries ascend through the spinal column, entering the brain through the magnum foramen, at the lower border of the pons the two vertebral arteries join together to form the basilar artery (vertebral basilar artery)
 
vestibulocerebellar tract:
a fiber tract that brings information from the semi-circular canals of the inner ear via the vestibular nucleus of the lower pons and medulla to the cerebellum; these fibers travel to the flocculi on the inferior cerebellar peduncle
 
vestibulospinal tract:
a fiber tract which brings information about the body's position in space to the antigravity muscles; the fastigial nucleus of the cerebellum sends messages to the vestibular nuclei in the lower pons and midbrain, from here the information is sent to lower motor neurons in the brain stem and spinal cord, runs from the vestibular nuclei located in the lower pons and medulla to the spinal nerves. It is involved in balance.
 
visual agnosia:
a condition in which an individual can see a visual stimuli, but is unable to associate it with meaning or identify its function; it represents a problem with meaning and may be a result of damage to the secondary visual areas  

W

 
watershed areas:
areas of the brain that are located beyond the ends of the vascular systems; these areas are particularly vulnerable to problems with blood supply
 
Wernicke's Aphasia:
also termed semantic aphasia
 
lesion is located in the posterior region of the left superior temporal gyrus or the first gyrus of the temporal lobe. Brodmann's areas 21 and 42 correspond to Wernicke's area (FitzGerald, 1997). The damage often extends into the parietal lobe, affecting the angular gyrus (Brodmann's area 39). The major impairment is semantic. With severe Wernicke's aphasia there is usually a severe impairment in auditory comprehension. Speech, while fluent, is semantically inappropriate and paraphasic. The speech of Wernicke's patients is sometime called cocktail hour speech. Comprehension and expression tend to be equally impaired. Patients with moderate Wernicke's can get the point in conversations but miss many specifics (Brookshire, 1997). Articulation is normal, Melodic Line is unaffected. If one ignores the content, the form of the patient's speech may sound normal. They have long, grammatically well formed utterances that contain almost no meaning, speech is paragrammatical, paraphasias are common (FitzGerald, 1997). Repetition is typically poor. Patients may use augmentation. Also due to auditory comprehension deficits, the patient may repeat the examiner's words without understanding them. Word finding problems are very common. Confrontational naming is typically impaired. Auditory comprehension is impaired.
Alexia with agraphia may be present, and press of speech also characterizes Wernicke's aphasics
 
Wernicke's area:
an area of the brain, located in the temporal lobe on the posterior portion of the superior temporal gyrus, that is associated with the ability to understand and produce meaningful speech; a lesion in this area will cause Wernicke's aphasia

X 

Y 

Z

 
zygomaticus (oral cavity):
lip muscle of the oral cavity with the obicularis oris and buccinator all three are innervated by the facial nerve (CN. VII).