Thalamocortical inhibitory dynamics support conscious perception

Byoung-Kyong Min,Hyun Seok Kim,Dimitris A Pinotsis,Dimitrios Pantazis

doi:10.1016/j.neuroimage.2020.117066

Abstract

Whether thalamocortical interactions play a decisive role in conscious perception remains an open question. We presented rapid red/green color flickering stimuli, which induced the mental perception of either an illusory orange color or non-fused red and green colors. Using magnetoencephalography, we observed 6-Hz thalamic activity associated with thalamocortical inhibitory coupling only during the conscious perception of the illusory orange color. This sustained thalamic disinhibition was temporally coupled with higher visual cortical activation during the conscious perception of the orange color, providing neurophysiological evidence of the role of thalamocortical synchronization in conscious awareness of mental representation. Bayesian model comparison consistently supported the thalamocortical model in conscious perception. Taken together, experimental and theoretical evidence established the thalamocortical inhibitory network as a gateway to conscious mental representations.

Highlights

The experience of conscious perception is essential to everyday life, but the neural correlates underlying this process remain under debate
The thalamic reticular nucleus (TRN) acts as an integrative junction and serves as inhibitory control over the interactive thalamocortical circuits (Min, 2010). Given this TRN-mediated inhibitory regulation over thalamocortical interactions during brain function, in the present study we explored whether such a thalamic disinhibition plays an essential role in conscious perception of mental representations
MEG analysis relied on N1 1⁄4 10 participants for fusion and N2 1⁄4 8 for non-fusion, because each participant responded subjectively whether conscious perception of fusion color occasionally occurred or not, and some participants experienced both percepts while others experienced only one percept

Summary

Introduction

The experience of conscious perception is essential to everyday life, but the neural correlates underlying this process remain under debate. One view posits that conscious experience occurs primarily within the cortex (Crick and Koch, 2003; Dehaene and Changeux, 2011; Romijn, 2002). Consistent with this view, there are a multitude of anatomical cortico-cortical connections that are reciprocal to feedforward connections, forming extensive intra-cortical feedback loops (Nieuwenhuys et al, 2007). A second view postulates that subcortical structures, prominently the thalamus, are essential for conscious perception (Penfield and Feindel, 1975; Ward, 2011). This controversy on the neural basis of conscious perception has recently brought increased attention to the role of thalamocortical networks in conscious perception (Edelman and Tononi, 2008; John, 2002; Llinas et al, 1998)

Objectives

Methods

Results

Conclusion