Context-sensitive V1 activity that depends on both coherence and surprise

Abstract

We investigate how information processing in the early visual cortex, which is tuned to the statistical regularities of sensory inputs, depends critically on the context in which those inputs occur. Neurobiologically inspired computational frameworks of visual processing emphasise functional interactions between higher and lower cortical areas, whereby higher areas with larger receptive fields send top-down (feedback) signals that contextualise bottom-up (feedforward) processing in lower areas. In this human fMRI study, we use visual scenes in which information was partially and temporarily occluded to test cortical processing in the corresponding retinotopic area within V1. By temporally varying the onsets of bottom-up (feedforward) sensory input in one quadrant of the visual field (the target area) and the onset of its surrounding context, we examined how consistent versus inconsistent surrounds influence the processing of bottom-up input to V1 before or after the arrival of feedback signals. We found that responses in the target region depended on both the consistency and the timing of the surround stimuli. Information in the surround increased the V1 BOLD response to the target compared with when the target was presented alone. However, when the target became temporally predictable by a consistent surround shown before the target, the response to the target neither increased nor decreased. We discuss our results in the light of how the neocortex transmits informative and coherent signals.