Neuroscience of consciousness
January 1, 2022
Joachim Bellet, Marion Gay, Abhilash Dwarakanath et al.
57 citations
Neuronal populations in the macaque prefrontal cortex (PFC) reliably encode visual stimuli even under conditions that challenge conscious perception and reduce post-perceptual processing. Recordings from the ventrolateral PFC during isolated trials and rapid serial visual presentation (RSVP) showed that stimulus identity could be decoded from population activity, with first signals at 60 ms and peak information at 150 ms. In RSVP, decoding accuracy dropped to chance by 200 ms as the next stimulus became decodable. Decoding in ventrolateral PFC was stronger than in posterior parietal cortex. The findings indicate PFC encodes visual information under conditions that limit conscious access and post-perceptual elaboration, raising questions about whether this reflects conscious access, phenomenal consciousness, or preconscious bottom-up processing.
Nature communications
March 11, 2024
Andrea I Luppi, Lynn Uhrig, Jordy Tasserie et al.
43 citations
Loss of consciousness under anesthesia increasingly constrains brain activity to follow the brain's physical structure, collapsing hierarchical cortical organization across scales. This effect was observed with three different anesthetics—propofol, sevoflurane, and ketamine—and was reversed by electrically stimulating the central thalamus, which also restored behavioral signs of arousal. Stimulating the ventral lateral thalamus did not produce these effects, showing specificity. The findings identify distributed brain signatures of consciousness that are orchestrated by particular thalamic nuclei.
bioRxiv Preprint Server
June 4, 2020
Camilo Miguel Signorelli, Lynn Uhrig, Morten Kringelbach et al.
preprint
Anesthesia disrupts the brain's hierarchical organization, which may be a key mechanism behind loss of consciousness. By analyzing resting-state fMRI data from awake and anesthetized macaques, the authors found that anesthesia reduces the flexibility and richness of brain dynamics, making them more rigid and driven by brain structure. The depth of anesthesia and the specific anesthetic agent used both modulate these effects. Spatial and temporal aspects of cortical hierarchy are affected differently, involving distinct brain networks. The findings suggest that a breakdown in brain hierarchy is a new signature of unconsciousness.