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Abstract:
The present study used event-related functional magnetic
resonance imaging (fMRI) to investigate the neural substrate of
spatial attention shifts, in humans. We examined shifts for both
visual and tactile targets to address possible multimodal
mechanisms. On a trial-by-trial basis, an auditory cue symbolically
indicated the likely location (left or right hemifield) for the
target. Unpredictably, a visual or tactile target was then
presented, either at the cued location (valid trials, 80%), or in
the opposite side, inducing an automatic shift of attention
(invalid trials, 20%). While maintaining central fixation, subjects
judged the elevation (up versus down) of targets regardless of
their side. Comparison of brain activity for invalid minus valid
trials showed activation of the temporo-parietal junction and
regions of the inferior frontal cortex, irrespective of the
modality of the targets. These results highlight the multimodal
role of these areas and their involvement in spatial attention,
thus extending previous findings in non-human primates, which
implicate these regions in the crossmodal spatial
integration.
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