Parallel and functionally segregated processing of task phase and conscious content in the prefrontal cortex

Vishal Kapoor,Nikos K Logothetis,Michel Besserve,Theofanis I Panagiotaropoulos

doi:10.1038/s42003-018-0225-1

Abstract

The role of lateral prefrontal cortex (LPFC) in mediating conscious perception has been recently questioned due to potential confounds resulting from the parallel operation of task related processes. We have previously demonstrated encoding of contents of visual consciousness in LPFC neurons during a no-report task involving perceptual suppression. Here, we report a separate LPFC population that exhibits task-phase related activity during the same task. The activity profile of these neurons could be captured as canonical response patterns (CRPs), with their peak amplitudes sequentially distributed across different task phases. Perceptually suppressed visual input had a negligible impact on sequential firing and functional connectivity structure. Importantly, task-phase related neurons were functionally segregated from the neuronal population, which encoded conscious perception. These results suggest that neurons exhibiting task-phase related activity operate in the LPFC concurrently with, but segregated from neurons representing conscious content during a no-report task involving perceptual suppression.

Highlights

The role of lateral prefrontal cortex (LPFC) in mediating conscious perception has been recently questioned due to potential confounds resulting from the parallel operation of task related processes
Using a no-report task[12] of binocular flash suppression (BFS)[13,14], which allows the successful dissociation of sensory input from phenomenal awareness, it was found that the majority of stimulus selective cells (60–90% depending upon the strength of selectivity) encoded subjective visibility[11]
Electrophysiological activity was recorded from 1285 single units with twisted wire tetrodes[29] in the LPFC of three animals while they passively fixated during the task of BFS (Fig. 1)

Summary

Introduction

The role of lateral prefrontal cortex (LPFC) in mediating conscious perception has been recently questioned due to potential confounds resulting from the parallel operation of task related processes. Task-phase related neurons were functionally segregated from the neuronal population, which encoded conscious perception These results suggest that neurons exhibiting task-phase related activity operate in the LPFC concurrently with, but segregated from neurons representing conscious content during a no-report task involving perceptual suppression. Using a no-report task[12] of binocular flash suppression (BFS)[13,14], which allows the successful dissociation of sensory input from phenomenal awareness, it was found that the majority of stimulus selective cells (60–90% depending upon the strength of selectivity) encoded subjective visibility[11] This finding gave credence to the ‘frontal lobe hypothesis’[15], and theoretical frameworks such as the higher order[16] and global workspace theories[17,18] which postulate PFC as an essential anatomical node mediating consciousness. Our results suggest that different and functionally segregated neural populations in the LPFC encode conscious perception and task monitoring functions and operate in parallel during a no-report task of perceptual suppression

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