Journal of Neuroscience, Vol 13, 1202-1226, Copyright © 1993 by Society for Neuroscience
A PET study of visuospatial attention
M Corbetta, FM Miezin, GL Shulman and SE Petersen
Department of Neurology and Neurological Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.
Positron emission tomography (PET) was used to identify the neural systems
involved in shifting spatial attention to visual stimuli in the left or
right visual field along foveofugal or foveocentric directions.
Psychophysical evidence indicated that stimuli at validly cued locations
were responded to faster than stimuli at invalidly cued locations. Reaction
times to invalid probes were faster when they were presented in the same
than in the opposite direction of an ongoing attention movement. PET
evidence indicated that superior parietal and superior frontal cortex were
more active when attention was shifted to peripheral locations than when
maintained at the center of gaze. Both regions encoded the visual field and
not the direction of an attention shift. In the right superior parietal
lobe, two distinct responses were localized for attention to left and right
visual field. Finally, the superior parietal region was active when
peripheral locations were selected on the basis of cognitive or sensory
cues independent of the execution of an overt response. The frontal region
was active only when responses were made to stimuli at selected peripheral
locations. These findings indicate that parietal and frontal regions
control different aspects of spatial selection. The functional asymmetry in
superior parietal cortex may be relevant for the pathophysiology of
unilateral neglect.