Figure 6.

The time-point-by-time-point difference in activity between homologous regions in opposite hemispheres much better indicates the locus of spatial attention compared with activity from individual regions. This figure is identical to Figure 5, except that the data are derived as the trial-by-trial, time point-by-time point difference in the activity between homologous regions in the left and right hemispheres. A-D, Each panel displays how well the difference in BOLD activity between homologous regions in opposite hemispheres can discriminate whether attention is directed toward the contralateral or ipsilateral target location, as quantified with the ADI. A, B, Subdivisions of visual cortex, each of which represents the target locations. C, D, Other regions across the brain with activity varying with the locus of attention. Note that the shapes of these curves are nearly identical to the curves from the individual regions, but the scales are much different. L, Left; R, right.