When simple cells are stimulated with drifting gratings for several seconds, two kinds of aftereffects are seen. Response amplitude decreases, and response timing is retarded. The change in timing comes about through a delay in the onset of the response to each cycle of the grating. The response offset is not affected. The histograms in Figure 1 show responses to a grating drifting at 2Hz in control and adapted states. In this case, both amplitude is reduced and onset is delayed.

For further details, see "Adaptation aftereffects in single neurons of cat visual cortex: response timing is retarded by adapting", Visual Neuroscience 12: 191-205, 1995.

One of the questions investigated in this poster is whether these timing aftereffects seen with moving stimuli are due to some nonlinear process that is tied to dynamic interactions. It will be shown below that the aftereffects can be understood in a fairly simple way, with the only nonlinearity being rectification.

Figure 1

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