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gordon shulman research scientist |
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Current studies are directed at using functional magnetic
resonance imaging (FMRI) to understand visual perception and attention
in healthy adults. Since far more visual information is imaged on the
retina than can be processed, attentional selection mechanisms are
necessary to insure that only important information is analyzed.
Similarly, selection mechanisms are necessary to insure that we respond
to only those stimuli or events which are relevant to our goals. Work
in this and other laboratories has shown that attention can powerfully
modulate the response to a stimulus throughout visual cortex. FMRI is
currently being used to study the visual and extravisual pathways by
which advance information concerning different properties of a test
object (e.g. its location, motion, color, etc) modulates areas in the
visual system. Two different types of neural signals underlie these
modulations: 'instruction signals' that insure that selection
mechanisms are properly set by the advance information, and attentional
modulations that reflect the effects of that set on the sensory
activity evoked by subsequent events. Our research takes advantage of
the temporal resolution of fMRI to separately image these signals over
the whole brain.
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