A dynamic bifurcation mechanism explains cortex-wide neural correlates of conscious access.
Ulysse Klatzmann, Sean Froudist-Walsh, Daniel P Bliss, Panagiota Theodoni, Jorge Mejías, Meiqi Niu, Lucija Rapan, Nicola Palomero-Gallagher, Claire Sergent, Stanislas Dehaene, Xiao-Jing Wang
Cell reports March 25, 2025 DOI: 10.1016/j.celrep.2025.115372 via PubMed
Summary
AI-generated from the abstractConscious access involves 'ignition,' an all-or-none activation across cortical areas. Computer simulations of a detection task using a mesoscale connectome-based model of the macaque cortex reveal a dynamic bifurcation mechanism that produces ignition in a network of associative regions. A hierarchical NMDA/AMPA receptor gradient is critical: fast AMPA receptors drive feedforward signal propagation, while slow NMDA receptors in feedback pathways shape and sustain the ignited network. The model suggests higher NMDA-to-AMPA receptor ratios in sensory areas compared to association areas, a prediction supported by in vitro autoradiography data. The model accounts for diverse behavioral and physiological phenomena linked to consciousness.
Study at a glance
| Characteristics | Computational modeling study Peer reviewed |
|---|---|
| Population | Macaque cortex (modeled) |
| Keywords | Ampa Cp: neuroscience Nmda Access consciousness Computational model |
| Citations | 14 |
| Key finding | A hierarchical NMDA/AMPA receptor gradient along the cortical hierarchy enables ignition, with higher NMDA-to-AMPA ratios in sensory areas than association areas, as predicted by the model and supported by autoradiography data. |
Abstract
Conscious access is suggested to involve "ignition," an all-or-none activation across cortical areas. To elucidate this phenomenon, we carry out computer simulations of a detection task using a mesoscale connectome-based model for the multiregional macaque cortex. The model uncovers a dynamic bifurcation mechanism that gives rise to ignition in a network of associative regions. A hierarchical N-methyl-D-aspartate (NMDA)/α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor gradient plays a critical role: fast AMPA receptors drive feedforward signal propagation, while slow NMDA receptors in feedback pathways shape and sustain the ignited network. Intriguingly, the model suggests higher NMDA-to-AMPA receptor ratios in sensory areas compared to association areas, a prediction supported by in vitro autoradiography data. Furthermore, the model accounts for diverse behavioral and physiological phenomena linked to consciousness. This work sheds light on how receptor gradients along the cortical hierarchy enable distributed cognitive functions and provides a biologically constrained computational framework for investigating the neurophysiological basis of conscious access.