The characteristic patterns of neuronal avalanches in mice under anesthesia and at rest: An investigation using constrained artificial neural networks.

Erik D Fagerholm,Erik D Fagerholm,Martin Dinov,Thomas Knöpfel,Robert Leech,Robert Leech

doi:10.1371/journal.pone.0197893

Erik D Fagerholm, Erik D Fagerholm + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0197893

Copy DOI

Abstract

Local perturbations within complex dynamical systems can trigger cascade-like events that spread across significant portions of the system. Cascades of this type have been observed across a broad range of scales in the brain. Studies of these cascades, known as neuronal avalanches, usually report the statistics of large numbers of avalanches, without probing the characteristic patterns produced by the avalanches themselves. This is partly due to limitations in the extent or spatiotemporal resolution of commonly used neuroimaging techniques. In this study, we overcome these limitations by using optical voltage (genetically encoded voltage indicators) imaging. This allows us to record cortical activity in vivo across an entire cortical hemisphere, at both high spatial (~30um) and temporal (~20ms) resolution in mice that are either in an anesthetized or awake state. We then use artificial neural networks to identify the characteristic patterns created by neuronal avalanches in our data. The avalanches in the anesthetized cortex are most accurately classified by an artificial neural network architecture that simultaneously connects spatial and temporal information. This is in contrast with the awake cortex, in which avalanches are most accurately classified by an architecture that treats spatial and temporal information separately, due to the increased levels of spatiotemporal complexity. This is in keeping with reports of higher levels of spatiotemporal complexity in the awake brain coinciding with features of a dynamical system operating close to criticality.

Highlights

We explored the use of constrained artificial neural networks (ANNs) to identify the characteristic patterns created by neuronal avalanches in the mouse cortex
We evaluate the insights provided by our method of placing prior constraints on ANNs, as well as the potential of this approach to guide future research
Local perturbations within complex dynamical systems can trigger cascade-like events that spread across significant portions of the system [30]

Summary

Introduction

This allows us to: a) create maps showing the way in which characteristic avalanches are encoded within the hidden layers, and b) identify the points of origin of the avalanches, together with their trajectories across the cortex for both the anesthetized and awake states. We begin by determining which ANN architectures are able to classify avalanches detected in voltage imaging data with the lowest mean squared error (MSE), in both the anesthetized and awake states.

Results

Conclusion