Thalamocortical Communication in the Awake Mouse Visual System Involves Phase Synchronization and Rhythmic Spike Synchrony at High Gamma Frequencies.

Samuel S Mcafee,Mukesh Dhamala,Detlef H Heck,Yu Liu

doi:10.3389/fnins.2018.00837

Abstract

In the neocortex, communication between neurons is heavily influenced by the activity of the surrounding network, with communication efficacy increasing when population patterns are oscillatory and coherent. Less is known about whether coherent oscillations are essential for conveyance of thalamic input to the neocortex in awake animals. Here we investigated whether visual-evoked oscillations and spikes in the primary visual cortex (V1) were aligned with those in the visual thalamus (dLGN). Using simultaneous recordings of visual-evoked activity in V1 and dLGN we demonstrate that thalamocortical communication involves synchronized local field potential oscillations in the high gamma range (50–90 Hz) which correspond uniquely to precise dLGN-V1 spike synchrony. These results provide evidence of a role for high gamma oscillations in mediating thalamocortical communication in the visual pathway of mice, analogous to beta oscillations in primates.

Highlights

Sensory processing requires selective and effective communication between neuronal groups, and this is influenced by the temporal alignment of regional oscillations (Fries et al, 2007; Womelsdorf et al, 2007; Bastos et al, 2015; Fries, 2015)
V1 oscillation amplitude increased in the high beta/low gamma (20–35 Hz) and high gamma ranges (50–90 Hz), the latter of which was higher in frequency and broader in bandwidth than previously reported narrowband gamma (Saleem et al, 2017; Veit et al, 2017b)
The dorsolateral geniculate nucleus of the thalamus (dLGN) local field potential (LFP) showed no such increase in beta or low gamma but did show increased high gamma amplitude, with frequencies matching those in V1

Summary

INTRODUCTION

Sensory processing requires selective and effective communication between neuronal groups, and this is influenced by the temporal alignment of regional oscillations (Fries et al, 2007; Womelsdorf et al, 2007; Bastos et al, 2015; Fries, 2015). We hypothesized that one oscillation may be related to thalamocortical communication, and rhythmic neuronal activity in this band would occur synchronously in dLGN and V1 during the presentation of high contrast visual stimuli We addressed this by performing dual dLGN-V1 recordings of LFPs and spikes in awake, head-fixed mice, and asked whether high contrast images induce synchronized band-limited gamma oscillations in mouse dLGN and V1. High-contrast visual stimulation led to synchronized dLGN and V1 high gamma oscillations that were temporally aligned with coincident spikes These findings suggest that high gamma in mouse V1 constitutes a channel for thalamocortical communication, and this gamma rhythm may be frequency- and bandwidth-modulated by stimulus properties such as luminance and contrast

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ETHICS STATEMENT