Sensory readout accounts for adaptation

Abstract

AbstractSensory responses and behavior are strongly shaped by stimulus history. For instance, perceptual reports are sometimes biased towards previously viewed stimuli (serial dependence). Previous behavioral studies suggest that serial dependence is implemented via modulations in visual cortex, but neural evidence is lacking. We recorded fMRI responses while human participants performed a delayed orientation discrimination task. While behavioral reports were attracted to the previous stimulus, response patterns in sensory areas were repelled. We reconciled these opposing biases using a model where both sensory encoding and readout are shaped by stimulus history. Neural adaptation reduces redundancy at encoding and leads to the repulsive biases that we observed in visual cortex. Serial dependence is not implemented in visual cortex but rather by readout mechanisms that account for adaptation during encoding. The model suggests the visual system improves efficiency via adaptation while still optimizing behavioral readout based on the temporal structure of natural stimuli.