Fig. 14.
Orientation and spatial-frequency tuning functions for gratings with different contrasts (indicated in key). A and E: the divisive normalization model (DNM) neuron with the standard parameter set. B and F: the DNM neuron with a modified parameter set (hΘ = 40°, hF = 1.0 oct). C: orientation tuning of a simple striate cell (replotted from Skottun et al. 1987, Fig. 3A, anesthetized cat). G: frequency tuning of a simple striate cell (replotted from Skottun et al. 1987, Fig. 4A, anesthetized cat). D and H: effect of stimulus contrast on the bandwidths of the real neurons in C and G and of the DNM neuron in the orientation (D) and frequency (H) domains for the 2 parameter sets (key). A, B, E, and F: the size of the grating patch was 2.88°. The spatial frequency of the grating was 2.0 cpd for A and B, and its orientation was 0° for E and F. (See phenomena 17 and 18 in Table 1.)