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. Howard Hughes Medical Institute, https://ror.org/006w34k90 National Institutes of Health, https://ror.org/01cwqze88, 1R01NS138157-01, T32MH065214
  • ☆ Yσɠƚԋσʂ ☆@lemmy.mlOP
    0·
    4 hours ago

    Turns out that neural activity across both inferotemporal and prefrontal cortex alternates between a conscious mode and an unconscious mode around 15 times every second.

    Bistable illusions like the face-vase illusion suggest that conscious awareness is the result of an active process in which the brain selects one interpretation to reach awareness out of all possible ones. So, by showing two different images to the left and right eyes, it’s possible to fully control which image is consciously perceived and which remains unconscious. Responses from thousands of neurons in inferotemporal and prefrontal cortex were recorded using Neuropixels probes while presenting thousands of flash suppression stimulus pairs. And the data shows that neural activity rapidly alternates between two coordinated states.

    Notably, when the image was reconstructed reconstructed using neural activity from one of the states, it looked exactly like the conscious face, half of time, and exactly like the suppressed face the other half. This means that it’s possible to reconstruct in rich detail, just from neural activity, not only something that you consciously perceive, but also something that escapes your awareness.

    These findings show that representation of conscious and suppressed content alternates every 60 ms. And at the single-neuron level, cells concertedly switched their tuning every 60 ms, from representing the conscious face to the suppressed face. Thus the same population of neurons represent both what you’re aware of and what you’re not, at different moments of time. So conscious perception does not reside in a specific brain region, but rather a specific temporal phase.