Adaptation is Associated With a Rightward Shift in the f-I Curve
Contrast adaptation is associated with a rightward shift and compression of the contrast response function curve in cortical neurons (left). Similarily, adaptation to the intracellular injection of sinewave current in vitro is associated with a rightward shift in the f-I relation (right).
Therefore, hyperpolarization of cortical neurons can explain some of the effects of contrast adaptation in cortical pyramidal cells.
The data in the left hand trace is from: Sclar, G., Lennie, P., and DePriest, D.D. (1989) Contrast adaptation in striate cortex of macaque. Vision Res. 29: 747-755.