[Right hemisphere dominance for attention].
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Animals↗
Biomedical subjects
R T Watson
Publications and source records attributed to R T Watson.
Affect in subcortical aphasia.
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Affective Symptoms↗
Nonsensory neglect from parietotemporal lesions in monkeys.
Monkeys trained to perform with the extremity contralateral to a stimulus had unilateral neglect induced by a parietotemporal lesion. Their performance was normal postoperatively when stimulated on the side contralateral to the lesion, but they made errors when stimulated on the normal side (the side ipsilateral to the lesion), often failing to use the extremity on the neglected side (the side contralateral to the lesion). Although we expected parietotemporal lesions to induce sensory neglect (failure to respond to contralateral stimuli), we could show only that these animals had a defect of intention (contralateral hypokinesia). In this respect, neglect induced by parietotemporal lesions is similar to that induced by frontal or medial thalamic lesions.
Animals↗
Thalamic neglect. Possible role of the medial thalamus and nucleus reticularis in behavior.
A patient had an ischemic infarction of the right medial thalamus, with a resultant contralateral neglect syndrome. We propose that the medial thalamic nuclei, particularly centromedian and parafascicularis (CMPF), are normally involved in the arousal-activation process by which an organism can be aroused by and respond to novel or important stimuli. Specifically, we propose that (1) the mesencephalic reticular formation subserves tonic arousal to novel or painful stimuli by inhibiting the nucleus reticularis thalami (NR) and (2) that selective attention is mediated by cortical input to NR. The CMPF is closely associated with motor systems (basal ganglia, ventrolateral nucleus of the thalamus [VL], and frontal lobes). A pathway involving CMPF, the frontal cortex, and the portion of NR associated with VL may be important in preparing the tonically aroused organism for action. Unilateral lesions of CMPF therefore induce an asymmetric hypokinesia, and bilateral lesions may induce akinetic mutism.
Arousal↗
Reconstructing the middle ear with homografts.
Fifty-one guinea pig temporal bones were examined up to 18 months (half of the animal's lifespan) after implanting a preserved composite tympano-ossicular monobloc homograft. The surgical technique is described in some detail to emphasize how an animal model may be used to reproduce some of the important features of human tympanoplasty. While histopathological changes are likely to influence the fate of middle-ear homografts, frank immunological rejection is rare although inflammation affecting the tympanic cavity may reverse immuno-tolerance.
Animals↗
Paroxysmal kinesigenic choreoathetosis and brain-stem atrophy.
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Adult↗
Perilymph fistulae.
A small series of 14 post-stapedectomy fistulae illustrates the varied aetiology. The long-term competence of the oval window seal may be ensured by making a small hole in the footplate. Contraction of ageing fibrous tissue contributes to late stapedectomy failures. Long-term follow-up is important, for any deterioration in hearing after stapedectomy may result from a perilymph leak.
Female↗
Thalamic neglect.
Three patients with right thalamic hemorrhage showed contralateral neglect and limb akinesia. They also had anosognosia, visuospatial disorders, and emotional flattening. In animals, neglect can be induced by lesions along a cortico-limbic-reticular loop including the intralaminar thalamic nuclei. We propose that an activation defect is responsible not only for the neglect and akinesia, but also for the visuospatial and emotional defects usually associated with right-hemisphere cortical dysfunction.
Aged↗
TIA, stroke, and mitral valve prolapse.
Eight patients with transient ischemic attacks, and three with partial nonprogressive strokes associated with mitral valve prolapse, are reported. No other etiology for their ischemic events was found. Only one episode of ischemia recurred on aspirin treatment, whereas none recurred on sodium warfarin therapy.
Adult↗
Changes in the symptoms of neglect induced by changing task strategy.
Six patients with left side unilateral neglect from lesions of the right cerebral hemisphere were tested with verbal and visuospatial crossing-out tasks. The symptoms of neglect were less severe with the visuospatial than with verbal tasks. We hypothesize that changes in the symptoms of neglect were produced because the tasks altered hemispheric arousal.
Aged↗
Operating table for guinea pig ear surgery.
This communication describes the construction and method of use of an adjustable operating table. The small table was designed especially to immobilize guinea pigs for experimental ear surgery.
Animals↗
Inhalation anesthesia with methoxyflurane for guinea pig ear surgery.
Anesthesia with methoxyflurane is ideal for long-term middle ear experiments on guinea pigs. This communication describes the use of a conventional pediatric anesthetic circuit that delivers a mixture of methoxyflurane and air by a face mask; it is effective, safe, and simple to use.
Anesthesia, Inhalation↗
Nonsensory neglect.
Five monkeys trained to perform with the extremity contralateral to a stimulus had unilateral neglect induced by frontal and reticular formation lesions. Postoperatively the performance of the animals was abnormal only on ipsilateral stimulation, which suggests that the mechanism underlying neglect in these subjects is not deafferentation of sensory inattention but a defect of intention.
Animals↗
Myokymia, muscle hypertrophy and percussion "myotonia" in chronic recurrent polyneuropathy.
Three unusual features were observed in a patient with chronic relapsing polyneuropathy: myokymia, muscle hypertrophy, and prolonged contraction in response to muscle percussion. Low nerve conduction velocity and conduction block were demonstrated in all motor nerves tested, indicating a demyelinating peripheral neuropathy. Myokymia was caused by spontaneous motor unit activity which was shown to originate in peripheral nerves, since it persisted after nerve block and was abolished by regional curarization. Muscle hypertrophy was attributed to increased peripheral nerve activity, and the prolonged contraction of muscle in response to direct percussion was attributed to irritability of intramuscular nerve terminals.
Adult↗
Hypoarousal in patients with the neglect syndrome and emotional indifference.
Physiologic theories of emotion suggest that activation is important in the experience of emotion; patients exhibiting "neglect" as a consequence of right parietotemporal of dysfunction show flattened affect. We studied arousal in patients with lesions of the right hemisphere who also exhibited emotional indifference, in aphasic patients with lesions of the left hemisphere, and in non-brain-damaged controls, by stimulating the forearm ipsilateral to the side of the brain lesion while recording galvanic skin responses (GSRs) from the fingers on the same side. The group exhibiting neglect had lower GSRs than aphasic patients or non-brain-damaged controls. Aphasic patients had higher GSRs than non-brain-damaged controls. These results suggest that neglect is associated with disturbances in bilateral arousal and that this disorder of arousal may be responsible in part for flattened affect. The heightened GSR in aphasic patients may reflect disinhibition, which might be partly responsible for increased emotionality in these patients.
Affective Symptoms↗
Evoked potential in neglect.
The evoked potential was studied in Macaca speciosa before and after they received a lesion inducing neglect. Significant evoked potential changes associated with neglect were seen only in late components (N2, P3). These observations support the hypothesis of the arousal-attention mechanism of neglect.
Animals↗
Retinal degeneration without pigment alterations in progressive external ophthalmoplegia.
A 56-year-old black man had annular visual field defects and retinal electrophysiologic dysfunction with chronic progressive external ophthalmoplegia and no pigmentary abnormalities in the fundus. Because the association of retinal disease with neurodegenerative states has generally been based on the observation of pigmentary changes, the patient's fields were erroneously interpreted as the nerve fiber bundle defects of glaucoma.
Chronic Disease↗