Frontal-posterior loop integrating captured attention into visual consciousness in the human brain

Abstract

AbstractThe emergence of subjective consciousness in the brain remains a profound puzzle, with attention at its core. Despite enduring debates on whether consciousness requires attention, the mechanisms by which attention becomes integrated into consciousness have been insufficiently explored. Here we show it is the bottom-up captured attention rather than top-down supplied attention that contributes to conscious experience, and revealed landmark neural dynamics underlying this process. Combining psychophysics with intracranial electroencephalography (iEEG) data from 21 epilepsy patients, we examined consciousness-related neural activity (visible versus invisible) under conditions of both poor and sufficient integration of attention into consciousness. In scenarios where attention was poorly integrated, we observed sustained and homogeneous neural representations in the posterior brain, despite its functional disconnection from the frontal brain. This observation supports the proposal of a preconscious buffer state situated between unconscious and conscious states. Conversely, in scenarios where attention was sufficiently integrated into consciousness, even before frontal-posterior coupling was established (thus still in a preconscious state), supplied attention primed the entire brain for subsequent attentional integration. This priming involved selecting signals-to-be-perceived by the posterior brain and stabilizing attentional supply by the frontal brain. Subsequently, the functional coupling between the frontal and posterior brain formed a closed loop. Notably, within this loop, what continuously broadcasted were coarse-grained binary signals of consciousness emergence, opposing views attributing consciousness to the global broadcasting of fine-grained contents. These findings show what and how attention gets integrated into visual consciousness, and the resulting outcomes call for a significant revision of current theories of consciousness. In response, we propose an attentional integration model of consciousness (AIM) aimed at reconciling the sharp discrepancies in this field.