Figure 4.
Adaptation increases the proportion of failures in the responses of A1 neurons. A, B, Spike-count distributions for two neurons (A, B), for frequencies f1 and f2, when they were standards (black bars) or deviants (gray bars). Solid lines, Fits of Poisson distributions, based on non-zero counts only. C, The parameter pf indicates the observed probability of zero-counts minus predicted probability from the Poisson fits, plotted for standards against deviants. D, More failures for standards than for deviants. Population means of pf for standards and deviants, grouped by firing rate, are shown. Note that each neuron contributes twice to this plot; for example, for the deviant it may contribute to a high firing-rate bin and for the standard it may contribute to a lower firing-rate bin. Number of neurons averaged for each bar, from left to right: 57, 38, 13, 21, 11, 6, 16, and 32. E, Adaptation index SI, computed for non-zero counts only. Data are for stimulus condition 2 (p = 90/10%; Δf = 0.37).