State-Dependent Synchrony and Functional Connectivity in the Primary and Secondary Whisker Somatosensory Cortices.

Mohamed Khateb,Yitzhak Schiller,Jackie Schiller

doi:10.3389/fnsys.2021.713397

Mohamed Khateb, Yitzhak Schiller + Show 1 more

Open Access

https://doi.org/10.3389/fnsys.2021.713397

Copy DOI

Abstract

Synchronized activity plays an important role in sensory coding and memory and is a hallmark of functional network connectivity. However, the effect of sensory activation on synchronization and cortical functional connectivity is largely unknown. In this study, we investigated the effect of whisker activation on synchronization and functional connectivity of the primary (wS1) and secondary (wS2) whisker somatosensory cortices at the single-cell level. The results showed that during the spontaneous pre-stimulus state, neurons tended to be functionally connected with nearby neurons which shared similar tuning characteristics. Whisker activation using either ramp-and-hold stimulation or artificial whisking against sandpaper has significantly reduced the average overall pairwise synchronization and functional connectivity within the wS1 barrel and wS2 cortices. Whisker stimulation disconnected approximately a third of neuronal pairs that were functionally connected during the unstimulated state. Nearby neurons with congruent tuning properties were more likely to remain functionally connected during whisker activation. The findings of this study indicated that cortical somatosensory networks are organized in non-random small world networks composed of neurons sharing relatively similar tuning properties. Sensory whisker activation intensifies these properties and further subdivides the cortical network into smaller more functionally uniform subnetworks, which possibly serve to increase the computational capacity of the network.

Highlights

Synchronization of neural activity is a fundamental feature of the cortical network
This study investigated the effect of whisker activation on neural synchrony and functional connectivity of the wS1 cortex through simultaneously recording the single-unit activity from multiple neurons located in different neocortical layers of wS1 using multicontact single shaft electrodes while stimulating the contralateral whiskers (Figures 1A–D)
We investigated the effect of whisker activation on synchronization and functional connectivity of the primary wS1 and secondary wS2 somatosensory whisker cortices

Summary

Introduction

Synchronization of neural activity is a fundamental feature of the cortical network. Neuronal responses in the cortex are correlated on spatio-temporal scales ranging from slow blood oxygenation level-dependent (BOLD) signals to oscillations of the extracellular field potentials. Synchrony was widely used to define functional connectivity within the brain neural network using either resting-state BOLD MRI signals (Blatow et al, 2007; Wang et al, 2013; Gordon et al, 2017), EEG and ECoG signals (Hummel and Gerloff, 2005; Rose and Büchel, 2005; Schoffelen and Gross, 2009), and pairwise correlated firing of individual neurons (Temereanca et al, 2008; Bruno, 2011; Constantinople and Bruno, 2011). The results showed that whisker activation by either the passive ramp-and-hold stimulation or artificial whisking against sandpaper has decreased pairwise synchronization and disconnected functional connections between neuronal pairs in a distance and tuning-dependent manner. Whisker activation resulted in a smaller world network that preferred functional connectivity between neurons sharing similar tuning properties in somatosensory cortices

Methods

Results

Conclusion