Figure 4.
Mutual information with a non-monotonic response function. A, The mutual information for three different systems: (1) one ON and one OFF cell; (2) two ON cells; and (3) one U-cell with a U-shaped nonlinearity and an ON cell. Although the first two systems divide the stimulus range into three regions, the last divides it into a total of four regions and transmits a maximum of log2(4) = 2 bits of information. Inset, The total mean spike count (normalized by Nmax). B, The optimal thresholds of the response functions for the three systems in A when constraining Nmax. Right, Optimal response functions in the limits of low and high Nmax.