1999 Fiscal Year Final Research Report Summary
Central nervous system plasticity in patients with intractable epilepsy, with special reference to unmasking phenomenon.
| Project/Area Number |
10671334
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cerebral neurosurgery
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| Research Institution | University of Occupational and Environmental Health |
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Principal Investigator |
URASAKI Eiichirou University of Occupational and Environmental Health, Department of Neurosurgery, Assistant professor, 医学部, 講師 (20203599)
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| Co-Investigator(Kenkyū-buntansha) |
TSUJI Sadatoshi University of Occupational and Environmental Health, Department of Neurosurgery, Professor, 医学部, 教授 (30117171)
AKAMATSU Naoki University of Occupational and Environmental Health, Department of Neurosurgery, Assistant, 医学部, 助手 (10299612)
WADA S University of Occupational and Environmental Health, Department of Neurosurgery, Assistant professor, 医学部, 助教授 (30094056)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Brain / plasticity / somatosensory evoked potentials / ischemic anesthesia / touch and movement interference / unmasking / surround inhibition / partial saturation |
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| Research Abstract |
Objective : We examined whether unmaking phenomenon is present in human adult brain by analyzing changes of somatosensory evoked potentials (SEPs) during ischemic anesthesia to finger. They Were compared with those during touch or movement interference. High frequency oscillations (500-900) were also studied to differentiate these SEP changes.
Methods : SEPs were directly recorded in the vicinity of central sulcus in patients with intractable epilepsy who required implantation of chronic subdural electrodes. During electrical stimulation to a selected finger, ischemic anesthesia was induced by the legation of other finger' s base using rubber band. Touch interference was examined during electrical stimulation to the selected finger, by applying tactile stimulation to other finger (surround inhibition), or by applying tactile stimulation to the eclectically stimulated finger (partial inhibition). Movement interference was studied during electrical stimulation to the selected finger while
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other finger moved spontaneously.
Results : (1) During ischemic anesthesia to fingers, SEP changes became gradually apparent and tended to persist after the release of ischemia. (2) SEP changes during touch or movement interference were in part similar to those during ischemia, but were more remarkable. These interference effects were seen not only in area 3b, but also in area 1. (3) It was difficult to differentiate the SEP changes during ischemia, touch, and movement by the analysis of their high frequency oscillations.
Conclusions : Dynamic changes of neural network shortly after finger ischemia were demonstrated by SEP changes directly recorded on the human adult cortex. These changes seemed to hold for a while probably because of a new setting of the neural network. Some similarities were shown in SEP changes during ischemic anesthesia and during touch or movement interference. SEP changes during finger ischemia could not be related to unmasking phenomenon in this study, because at least SEP components within 40 msec demonstrated no enlargement of receptive field nor increase of responses. Less
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