# Reconstructing rodent brain signals during euthanasia with eigensystem realization algorithm (ERA)

## TL;DR

This study uses a mathematical algorithm to reconstruct brain signals in rats during euthanasia, revealing differences in brain complexity between awake and anesthetized animals.

## Contribution

The study introduces the use of the Eigensystem Realization Algorithm to analyze brain signal complexity during euthanasia in rodents.

## Key findings

- Anesthetized and awake brains show similar complexity before CO2 administration.
- Awake brains display increased complexity during euthanasia, suggesting heightened neuronal activity.
- Anesthetized brains show reduced complexity early in the euthanasia process.

## Abstract

We accurately reconstruct the Local Field Potential time series obtained from anesthetized and awake rats, both before and during CO2 euthanasia. We apply the Eigensystem Realization Algorithm to identify an underlying linear dynamical system capable of generating the observed data. Time series exhibiting more intricate dynamics typically lead to systems of higher dimensions, offering a means to assess the complexity of the brain throughout various phases of the experiment. Our results indicate that anesthetized brains possess complexity levels similar to awake brains before CO2 administration. This resemblance undergoes significant changes following euthanization, as signals from the awake brain display a more resilient complexity profile, implying a state of heightened neuronal activity or a last fight response during the euthanasia process. In contrast, anesthetized brains seem to enter a more subdued state early on. Our data-driven techniques can likely be applied to a broader range of electrophysiological recording modalities.