Figure 6. Adaptation of the spatio-temporal receptive field and gain.

(A) Center latency (time to peak of the temporal kernel) is shorter for spatio-temporal exponentially correlated noise. Histogram shows adaptation indices (corr−white)/(corr+white) for center latency (). (B,C) Changes in center latency (corr−white) for spatio-temporally correlated (B) and temporally correlated (C) stimuli, in milliseconds. Almost all cells have a decreased time to peak when responding to a correlated stimulus. (D) Adaptation indices, computed as in (A), for relative surround strength (surround/center ratio) show a slight skew toward a stronger surround for spatio-temporally correlated noise (). (E, F) Difference in surround strength for the spatio-temporal (E) and spatial (F) exponential stimuli. (G) Gain adaptation. Gains were defined as the slope of the LN model nonlinearity, and obtained separately for the response to white noise and to the spatio-temporally correlated exponential stimulus. Effective contrast, the standard deviation of the linear filter output, was similarly measured in both stimuli. The difference in gain, correlated value minus white noise value, is plotted against the difference in effective contrast. Increases in effective contrast tend to invoke compensating decreases in gain ().