Figure 5.

Multiunit RF estimate. A, We inverse Fourier transformed the model fit, giving the organization of central excitation (solid contours) and surrounding suppression (dashed). This field describes an envelope of contrast sensitivity to the sinusoidal carrier grating stimulating the RE (Fig. 4). Peak field sensitivity is normalized to 100. Contour interval is 10. B, We superimposed contours −5 and 5 on a stimulus that elicited vigorous responses; when the carrier grating stimulated central excitation, it was mostly absent from the surround suppressive regions as shown. In this and all subsequent figures, we rotated RFs so that the sinusoidal carrier grating is vertical and drifting right.