Human single neuron activity precedes emergence of conscious perception

Hagar Gelbard-Sagiv,Christof Koch,Itzhak Fried,Liad Mudrik,Michael R Hill

doi:10.1038/s41467-018-03749-0

Abstract

Identifying the neuronal basis of spontaneous changes in conscious experience in the absence of changes in the external environment is a major challenge. Binocular rivalry, in which two stationary monocular images lead to continuously changing perception, provides a unique opportunity to address this issue. We studied the activity of human single neurons in the medial temporal and frontal lobes while patients were engaged in binocular rivalry. Here we report that internal changes in the content of perception are signaled by very early (~-2000 ms) nonselective medial frontal activity, followed by selective activity of medial temporal lobe neurons that precedes the perceptual change by ~1000 ms. Such early activations are not found for externally driven perceptual changes. These results suggest that a medial fronto-temporal network may be involved in the preconscious internal generation of perceptual transitions.

Highlights

Identifying the neuronal basis of spontaneous changes in conscious experience in the absence of changes in the external environment is a major challenge
Patients first participated in a selectivity screening session, where they were presented with a large number of images to find ones that elicit selective responses in medial temporal lobe (MTL) neurons[32]
This study reports human single unit correlates of internally driven changes in the content of visual awareness in the medial temporal and frontal lobes

Summary

Introduction

Identifying the neuronal basis of spontaneous changes in conscious experience in the absence of changes in the external environment is a major challenge. We studied the activity of human single neurons in the medial temporal and frontal lobes while patients were engaged in binocular rivalry. We report that internal changes in the content of perception are signaled by very early (~-2000 ms) nonselective medial frontal activity, followed by selective activity of medial temporal lobe neurons that precedes the perceptual change by ~1000 ms Such early activations are not found for externally driven perceptual changes. Patients were engaged in either BR, where perceptual alternations were internally driven, or in a matched-duration replay condition, in which the perceptual alternations were externally driven by an actual stimulus change This opportunity to measure single cell activity in humans able to readily report their subjective experience allowed us to track the neural events that precede spontaneous alternations in perception. Medial frontal and medial temporal activity are persumably part of the chain of events that leads to an internal perceptual transition during rivalry

Methods

Results

Conclusion