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Prestimulus EEG alpha phase synchronicity influences N100 amplitude and reaction time

Published online by Cambridge University Press:  01 September 1998

ALBERT R. HAIG
Affiliation:
Department of Psychological Medicine, University of Sydney, Australia Cognitive Neuroscience Unit, Westmead Hospital, Sydney, Australia
EVIAN GORDON
Affiliation:
Department of Psychological Medicine, University of Sydney, Australia Cognitive Neuroscience Unit, Westmead Hospital, Sydney, Australia
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Abstract

The influence of the level of prestimulus alpha phase synchronicity on the N100 component and reaction time (RT) was examined, in target auditory oddball data from 25 normal subjects. Alpha phase synchronicity is a new measure consisting (for a given stimulus presentation) of the angular or circular variance of the alpha phase at stimulus onset across the parieto-occipital sites. The lower the angular variance, the higher the phase synchronicity (the more closely in phase the alpha activity across these sites) and vice versa. Subaveraged event-related potentials (ERPs) were formed for high and low prestimulus alpha phase synchronicity stimulus presentations. N100 amplitude was significantly greater in the high than the low phase synchronicity subaverages. In addition, RT was significantly reduced in the high prestimulus alpha phase synchronicity cases. Alpha phase synchronicity reflects an aspect of brain state that influences subsequent stimulus processing.

Type
Research Article
Copyright
© 1998 Society for Psychophysiological Research

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