Adaptation is a ubiquitous property of sensory systems. It is typically considered that neurons adapt to dominant energy in the ambient environment to function optimally. However, perceptual representation of the stimulus, often modulated by feedback signals, sometimes do not correspond to the input state of the stimulus, which tends to be more linked with feedforward signals. Here we investigated the relative contributions to cortical adaptation from feedforward and feedback signals, taking advantage of a visual illusion, the Flash-Grab Effect, to disassociate the feedforward and feedback representation of an adaptor. Results reveal that orientation adaptation is exclusively dependent on the perceived rather than the retinal orientation of the adaptor. Combined fMRI and EEG measurements demonstrate that the perceived orientation of the Flash-Grab Effect is indeed supported by feedback signals in the cortex. These findings highlight the important contribution of feedback signals for cortical neurons to recalibrate their sensitivity.
Bibliographical noteFunding Information:
This work was supported by the Beijing Science and Technology Project (Z171100000117003, Z181100001518002), Strategy Priority Research Program of Chinese Academy of Sciences (XDB32020200), Ministry of Science and Technology of China (2019YFA0707103) and National Natural Science Foundation of China (The General Program No. 31871107, 31930053). We thank Sophia M. He for proofreading the manuscript.