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Abstract:
A growing body of literature suggests that feedback modulation of early processing is ubiquitous and central to cortical computation. In particular stimuli with high-level content have been shown to suppress early visual regions, typically interpreted in the framework of predictive coding.
However, physical stimulus differences can preclude clear interpretations in terms of feedback. Here we examined activity modulation in V1-V2 during distinct perceptual states associated to the same physical input. This ensures that observed modulations cannot be accounted for by changes
in physical stimulus properties, and can therefore only be due to percept-related feedback from higher-level regions. We used a bistable dynamic stimulus that could either be perceived as a large illusory square or as locally moving dots. We found that perceptual binding of local elements into an illusory Gestalt led to spatially segregated modulations: retinotopic representations of illusory
contours and foreground were enhanced, while inducers and background suppressed. The results extend prior findings to the illusory-perceptual state of physically unchanged stimuli, and show also percept-driven background suppression in the human brain. Based on our prior work, we
hypothesize that parietal cortex is responsible for the modulations through recurrent connections in a predictive coding account of visual processing.
