Fig. 5.

Spatial weighting functions and radial weighing functions of two parvocellular neurons as measured with L-cone-isolating, M-cone-isolating, and luminance-modulated stimuli (conventions are as in Fig. 2). A, L-on/M-off neuron, 9° eccentric. The on-center/off-surround luminance response was used to define the receptive field center, outlined in white(see Materials and Methods). Note that neither the center cone type (L) nor the surround cone type (M) exhibits center/surround opponency (Fig. 1, arrow). B, M-off/L-on neuron, 11° eccentric. Although the signatures of the L-cone and M-cone responses are the same as in A, the M-off response dominates. Total region shown, 1.0° on a side; pixel size, 7.5 min. Delay between stimulus and response, 15–44 msec, the sum of the 15–30 and the 30–44 msec bins (see Materials and Methods). Because the luminance weighting function was much weaker than L-cone and M-cone weighting functions, it was multiplied by a factor of 2.0 to increase visibility. Conventions are as in Figure 2.