David Ress1,2, Sucharit Katyal2,
1Imaging Research Center, University of
Texas at Austin, Austin, TX, United States; 2Neurobiology,
University of Texas at Austin, Austin, TX, United States
measured the retinotopic organization of superior colliculus to direct visual
stimulation using a 90-wedge of moving dots that rotated around fixation.
The retinotopy of covert attention was measured using a full-field array of
moving dots. Subjects were cued to perform a task within a 90 portion of the
stimulus, and only the cue rotated around fixation. FMRI (1.2 mm voxels) data
shows retinotopic maps of both visual stimulation and covert attention that
are in registration with each other. Visual attention and stimulation
produced activity primarily in the superficial and intermediate laminae, but
attention activity was more superficial than stimulation.