A temporal hierarchy of object processing in human visual cortex

Abstract

Our brain builds increasingly sophisticated representations along the ventral visual pathway to support object recognition, but how these representations unfold over time is poorly understood. Here we characterized time-varying representations of faces, places, and objects throughout the pathway using human intracranial electroencephalography. For ~100 ms after an initial feedforward sweep, representations at all stages evolved to be less driven by low-order features and more categorical. Low-level areas like V1 showed unexpected, late-emerging tolerance to image size, and late but not early responses of high-level occipitotemporal areas best matched their fMRI responses. Besides aligned, simultaneous representational changes, we found a trial-by-trial association between concurrent response patterns across stages. Our results suggest fast, multi-areal recurrent processing builds upon initial feedforward processing to generate more sophisticated object representations.