1997 Fiscal Year Final Research Report Summary
ANALYSIS OF BRAIN POTENTIALS RELATING TO COGNITION AND RESPONSE TO EXTERNAL STIMULI
| Project/Area Number |
08670690
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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 |
Neurology
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| Research Institution | HIROSAKI UNIVERSITY |
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Principal Investigator |
OZAKI Isamu HIROSAKI UNIVERSITY,UNIVERSITY HOSPITAL Instructor, 医学部附属病院, 助手 (90241463)
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| Co-Investigator(Kenkyū-buntansha) |
YAEGASHI Yukoh DEPARTMENT OF SOCIAL SCIENCE,AKITA KEIJO COLLEGE, 地域社会学科, 講師 (30289756)
BABA Masayuki DEPARTMENT OF NEUROLOGY,HIROSAKI UNIV.SCHOOL OF MEDICINE,Associate Professor, 医学部, 助教授 (90106849)
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| Project Period (FY) |
1996 – 1997
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| Keywords | SOMATOSENSORY EVOKED POTENTIOALS / MEDIAN NERVE / CENTRAL CONDUCTION TIME / AGING / HIGH FREQUENCY OSCILLATIONS |
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| Research Abstract |
The early somatosensory cortical responses following median nerve stimulation include waves of various frequency range, as spontaneous EEG does. They consist of the parietal N20-frontal P20 and central P22 potentials both of which have 30-50 Hz range. We evaluated whether high frequency (>500Hz) components of somatosensory evoked potentials may underlie those cortical responses in healthy volunteers. We found that 600-800 Hz oscillations superimpose both the N20-P20 and P22 potentials. The peak frequency and amplitude of these high friquency components changed due to subjects' consciousness level or attention. It is therefore to be determined that high frequency oscillations may reflect cognition prosess. As to somatosensory central conduction time, we have reported that the onset time of the initial cortical response is correlated to subject's height and age. We also evaluated how to determine the cortical arrival time and have reported the optimal electrode positions at the scalp and recording methods.
As to somatosensory target and non-target paradigm by which the subject is instructed to react by the index finger extension following recognition of the somatosensory target stimuli, we have found that a reaction time was sometimes shorter than the peak latency of the P300 component. It is suggested that P300 may reflect not only cognition but post-decision process.
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