Neuronal avalanches imply maximum dynamic range in cortical networks at criticality

TL;DR

This study demonstrates that cortical networks exhibiting neuronal avalanches at criticality maximize their dynamic range, enhancing input processing capabilities, and links spontaneous activity to optimal network tuning.

Contribution

The paper provides experimental evidence that neuronal avalanches at criticality optimize cortical networks for input processing by maximizing dynamic range.

Findings

Neuronal avalanches occur at the critical state in cortical networks.

Balanced excitation and inhibition establish the critical state.

Maximized dynamic range correlates with neuronal avalanches at criticality.

Abstract

Spontaneous neuronal activity is a ubiquitous feature of cortex. Its spatiotemporal organization reflects past input and modulates future network output. Here we study whether a particular type of spontaneous activity is generated by a network that is optimized for input processing. Neuronal avalanches are a type of spontaneous activity observed in superficial cortical layers in vitro and in vivo with statistical properties expected from a network in a 'critical state'. Theory predicts that the critical state and, therefore, neuronal avalanches are optimal for input processing, but until now, this is untested in experiments. Here, we use cortex slice cultures grown on planar microelectrode arrays to demonstrate that cortical networks which generate neuronal avalanches benefit from maximized dynamic range, i.e. the ability to respond to the greatest range of stimuli. By changing the ratio of excitation and inhibition in the cultures, we derive a network tuning curve for stimulus processing as a function of distance from the critical state in agreement with predictions from our simulations. Our findings suggest that in the cortex, (1) balanced excitation and inhibition establishes the critical state, which maximizes the range of inputs that can be processed and (2) spontaneous activity and input processing are unified in the context of critical phenomena.