Figure 3.

Amplitude of fMRI responses to scotopic gratings in the representations of central versus peripheral visual fields, measured relative to a spatially uniform gray screen (i.e., baseline), in areas V1, V2, V3, and V4. Evoked activity in response to gratings limited to the central (radius = 0–3°) and peripheral (radius = 5–10°) eccentricities is indicated in cyan and yellow, respectively. Consistent with the retinal distribution of rods versus cones, and the maps in Figures 1 and 2, BOLD responses increased significantly in peripheral representations in the most retinotopically organized areas V1 and V2, but BOLD response decreases were found at central representations. Analogous peripheral versus central differences were reduced but remained significantly higher in area V3, but not significantly in V4. Error bars represent one standard error of the mean.