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Abstract:
Previous evidence has suggested that spatial rehearsal in
working memory is mediated through covert focusing of spatial
selective attention at memorized locations. Behavioral experiments
have revealed improvements in visual processing efficiency for
stimuli that fall in memorized locations--a signature of spatial
selective orienting. In addition, recent fMRI evidence has shown
enhanced responses in early visual areas contralateral to locations
held in working memory, consistent with previous neuroimaging
research regarding spatial selective attention. The present
research uses multi-channel recordings of event-related potentials
(ERP) to investigate the time-course of these spatial rehearsal
effects. During the delay period of a spatial working memory task,
behaviorally-irrelevant probe stimuli were flashed at both
memorized and non-memorized locations. Consistent with the
hypothesis of attention-based rehearsal, early ERP components were
enlarged in response to probes that overlapped memorized locations.
These visual modulations were highly similar in latency and
topography to those observed after explicit manipulations of
spatial selective attention in a parallel experimental condition
that employed an identical stimulus display.
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