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Abstract:
The fronto-parietal circuit has been suggested to play a key role in mediating conscious perception by multiple theories of consciousness. In contrast, it has been argued that activity in these regions instead reflects post-perceptual processes such as decision making and motor reports. We recently addressed this debate partly, by probing the prefrontal cortex during a no-report binocular rivalry paradigm (BR) wherein subjective experience of a subjects can be objectively measured without a volitional report. BR is a phenomenon, wherein unchanged and disparate visual input to corresponding retinal locations elicit in an observer a perceptual experience which vacillates in time between the two sensory signals. It therefore allows disentangling neural signals related to sensory input from subjective perception. While our recordings utilizing no-report BR revealed that prefrontal population response correlated with the perceptual state of the animal, it remained yet unexplored, if the neural activity in the parietal cortex is also perceptually modulated in the absence of motor reports. The present study investigated the neuronal activity with a multi-electrode array implanted in the posterior parietal cortex of a monkey experiencing no-report BR, and we observed that spiking activity is robustly modulated in concordance with transitions in conscious perception. Preliminary results suggest that the proportion of units displaying reliable perceptual modulation are higher than early sensory regions. Therefore, we find that neuronal discharges in the parietal cortex are correlated with subjective perception during visual competition. Taken together, our results reinstate the role of fronto-parietal circuit in mediating conscious perception.
