Rapid alternation of conscious and suppressed representations in primate brains

Neuropixels recordings in macaque inferotemporal and prefrontal cortex show the brain alternates between conscious and suppressed representations about 15 times per second during binocular flash suppression, according to a preprint whose authors declared no competing interests. During conscious micro-epochs a pure signal of the consciously perceived face image allowed accurate reconstruction of that image from neural activity, while during suppressed micro-epochs the signal instead tracked the suppressed stimulus; single neurons responded selectively to the conscious stimulus in conscious epochs and to the suppressed stimulus in suppressed epochs, with feature tuning amplified during conscious micro-epochs. The authors conclude that conscious access requires temporal selection beyond localization, since both inferotemporal and prefrontal cortex rapidly interleave conscious with suppressed content.

Abstract The neural correlates of consciousness remain elusive 1 . Previous studies found that high-level visual cortex is weakly modulated by conscious perception 2,3 , yet a pure signal of conscious perception has not been found anywhere in the brain. Here, we employed Neuropixels recordings across multiple face patches in inferotemporal and prefrontal cortex during a binocular flash suppression paradigm 4 , in which one of two images is consciously perceived while the other, though continuously present, is suppressed from awareness. We found that, during a constant stimulus and percept, the brain rapidly alternates, about 15 times per second, between conscious and suppressed micro-epochs. During conscious micro-epochs, a pure signal of conscious perception was present, allowing accurate reconstruction of the conscious image from neural activity. During suppressed micro-epochs this reversed: the pure signal now tracked the suppressed stimulus, allowing accurate reconstruction of the suppressed image. At the single-cell level, neurons responded selectively to the conscious stimulus and not to the suppressed stimulus during conscious micro-epochs; conversely, during suppressed micro-epochs, neurons responded selectively to the suppressed stimulus. Despite this apparent symmetry, the two epochs could be reliably distinguished, with feature tuning amplified during conscious micro-epochs. Recordings in prefrontal cortex yielded qualitatively similar results. Together, these findings show that both inferotemporal and prefrontal cortex rapidly interleave conscious with suppressed content, indicating that conscious access requires temporal selection beyond localization. Competing Interest Statement The authors have declared no competing interest. Funder Information Declared CC-BY 4.0 International license http://creativecommons.org/licenses/by/4.0/ .