Local and thalamic origins of correlated ongoing and sensory-evoked cortical activities.

Katayun Cohen-Kashi Malina,Ilan Lampl,Akiva N Rappaport,Boaz Mohar

doi:10.1038/ncomms12740

Katayun Cohen-Kashi Malina, Ilan Lampl + Show 2 more

Open Access

https://doi.org/10.1038/ncomms12740

Copy DOI

Abstract

Thalamic inputs of cells in sensory cortices are outnumbered by local connections. Thus, it was suggested that robust sensory response in layer 4 emerges due to synchronized thalamic activity. To investigate the role of both inputs in the generation of correlated cortical activities, we isolated the thalamic excitatory inputs of cortical cells by optogenetically silencing cortical firing. In anaesthetized mice, we measured the correlation between isolated thalamic synaptic inputs of simultaneously patched nearby layer 4 cells of the barrel cortex. Here we report that in contrast to correlated activity of excitatory synaptic inputs in the intact cortex, isolated thalamic inputs exhibit lower variability and asynchronous spontaneous and sensory-evoked inputs. These results are further supported in awake mice when we recorded the excitatory inputs of individual cortical cells simultaneously with the local field potential in a nearby site. Our results therefore indicate that cortical synchronization emerges by intracortical coupling.

Highlights

Thalamic inputs of cells in sensory cortices are outnumbered by local connections
In awake mice, we examined the effect of silencing cortical firing on the correlation between excitatory inputs of individually recorded cortical cells and a nearby local field potential (LFP) signal, whereas in anaesthetized mice, we simultaneously recorded the excitatory inputs of nearby pairs of neurons
Our results show that synchronized activity during ongoing activity emerges from intracortical inputs, rather than being driven by direct thalamic inputs

Summary

Introduction

Thalamic inputs of cells in sensory cortices are outnumbered by local connections. it was suggested that robust sensory response in layer 4 emerges due to synchronized thalamic activity. We report that in contrast to correlated activity of excitatory synaptic inputs in the intact cortex, isolated thalamic inputs exhibit lower variability and asynchronous spontaneous and sensory-evoked inputs These results are further supported in awake mice when we recorded the excitatory inputs of individual cortical cells simultaneously with the local field potential in a nearby site. We optogenetically silenced the cortex[38,39,40] while simultaneously performing whole cell and LFP recordings in awake mice and dual intracellular recordings in anaesthetized mice This enabled us to study the contribution of thalamic and cortical excitatory synaptic inputs to the subthreshold -correlated ongoing and sensory-evoked activities in the barrel cortex. Our experiments show that cortical synchrony is not inherited from thalamic inputs but rather depends on recurrent cortical activity

Methods

Results

Conclusion