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Abstract:
Abstract: The brain's ability to selectively switch attention
between modalities is necessary for efficient preferential
processing of behaviorally relevant stimuli. We examined the
mechanisms of this switching phenomenon in humans using high
density electrical mapping (64-channel). Endogenous auditory cues
instructed subjects to perform either an auditory or visual
discrimination (1.2s later) upon a compound auditory-visual
stimulus. We focused on the 1.2s post-cue, pre-stimulus period to
define the difference between auditory and visual attentional
switch effects. Previous studies, using visual cues, have shown a
difference in parietal-occipital~10Hz activity during this
timeframe. We proposed that this difference reflects a disengaged
visual system in preparation for anticipated auditory input which
is attentionally more relevant (Foxe et al., 1998). The current
study using endogenous auditory cues illustrated a similar effect
during the same period. When cued to attend to the auditory
modality and ignore the visual, the subjects exhibited
significantly higher parietal-occipital~10Hz amplitude, which began
400ms post-cue and lasted until the second stimulus. These findings
suggest that gating of the visual system occurs through similar
mechanisms regardless of the modality of the instructive cue. The
effects of this gating upon subsequent stimulus processing will
also be discussed.
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