Fig. 6.

Two possible mechanisms to explain the inverse relationship between contrast adaptation to grating and plaid stimuli as a function of reference probe contrast. (A) At low test contrasts, adaptation to component stimuli is most apparent, consistent with other psychophysical findings. As the contrast of the test probe increases it approaches the optimal range for a plaid detector, which acts to inhibit the activity of the neurons responding to the grating stimulus in V1. (B) Alternatively, the mechanism mediating plaid-selective adaptation could inhibit the responses of the neurons responding to the component gratings through lateral inhibition at the level in which the plaid itself is encoded.