Spatial attention affects brain activity in human primary visual cortex
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Communicated by Jacob Nachmias, University of Pennsylvania, Philadelphia, PA (received for review May 29, 1998)
Abstract
Functional MRI was used to test whether instructing subjects to attend to one or another location in a visual scene would affect neural activity in human primary visual cortex. Stimuli were moving gratings restricted to a pair of peripheral, circular apertures, positioned to the right and to the left of a central fixation point. Subjects were trained to perform a motion discrimination task, attending (without moving their eyes) at any moment to one of the two stimulus apertures. Functional MRI responses were recorded while subjects were cued to alternate their attention between the two apertures. Primary visual cortex responses in each hemisphere modulated with the alternation of the cue; responses were greater when the subject attended to the stimuli in the contralateral hemifield. The attentional modulation of the brain activity was about 25% of that evoked by alternating the stimulus with a uniform field.
Footnotes
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↵ † To whom reprint requests should be addressed at: The Salk Institute, La Jolla, CA 92037-1099. e-mail: boynton{at}salk.edu.
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A Commentary on this article begins on page 2585.
- ABBREVIATIONS:
- fMRI,
- functional MRI;
- MT+,
- motion-sensitive visual area;
- V1,
- primary visual cortex
- Copyright © 1999, The National Academy of Sciences
