A new no-report paradigm reveals that face cells encode both consciously perceived and suppressed stimuli.

During binocular rivalry, a constant visual stimulus produces a changing conscious percept. A concern has been that brain activity measured during rivalry might reflect the act of reporting the percept rather than the percept itself. This study recorded single neurons from face patches in the inferotemporal cortex of macaques using a no-report paradigm, inferring the animal's conscious percept from its eye movements. Large proportions of inferotemporal neurons represented the conscious percept even without active report. On single trials, both the conscious percept and the suppressed stimulus could be decoded. These findings indicate that inferotemporal cortex contains a true neural correlate of consciousness, consisting of a population code where single cells multiplex representation of the conscious percept and the physical stimulus.

Study at a glance

Abstract

A powerful paradigm to identify neural correlates of consciousness is binocular rivalry, wherein a constant visual stimulus evokes a varying conscious percept. It has recently been suggested that activity modulations observed during rivalry may represent the act of report rather than the conscious percept itself. Here, we performed single-unit recordings from face patches in macaque inferotemporal (IT) cortex using a no-report paradigm in which the animal's conscious percept was inferred from eye movements. We found that large proportions of IT neurons represented the conscious percept even without active report. Furthermore, on single trials we could decode both the conscious percept and the suppressed stimulus. Together, these findings indicate that (1) IT cortex possesses a true neural correlate of consciousness and (2) this correlate consists of a population code wherein single cells multiplex representation of the conscious percept and veridical physical stimulus, rather than a subset of cells perfectly reflecting consciousness.