# Pupillometry and brain-wide c-Fos mapping uncover multimodal mirror emotional contagion related networks of mice

## TL;DR

This study uses pupil measurements and brain activity to show how mice share emotions, revealing a shared neural network involved in emotional contagion.

## Contribution

The study introduces pupillometry as a novel method to measure emotional contagion in mice and identifies a shared brain network during this process.

## Key findings

- Pupil dilation effectively measures both direct and vicarious emotional responses in mice.
- Emotional contagion involves a broad network of 88 brain regions in observers and demonstrators.
- Visual cues alone can trigger emotional contagion, as shown by observer responses to videos of shocked mice.

## Abstract

Emotional contagion (ECo) represents a fundamental form of empathy. In this study, we used pupillometry to quantify ECo by assessing pupil responses of a mouse watching another mouse receive a tail shock. Pupil dilation effectively measured both direct and vicarious emotional response thresholds at the individual level through psychometric curve analysis. The pupillary ECo response diminished when the observer could not see the demonstrator, suggesting a multisensory process involving vision. Viewing videos of tail-shocked mice elicited a pupil response in the observer. Brain-wide c-Fos mapping revealed a broad network of 88 brain regions activated during ECo, with all areas activated in the demonstrator also engaged in the observer. Additionally, in some brain regions, correlated activation was detected between each observer-demonstrator pair, indicating that ECo promotes a shared neural state. These findings advance our understanding of the neural basis of shared emotions, with implications for analyzing neuropsychiatric disorder models.

•Pupillometry tracks direct and vicarious emotional responses•Visual cues alone can trigger emotional contagion•Emotional contagion recruits a distributed whole-brain network•Observers and demonstrators show coupled pupil and neural activation

Pupillometry tracks direct and vicarious emotional responses

Visual cues alone can trigger emotional contagion

Emotional contagion recruits a distributed whole-brain network

Observers and demonstrators show coupled pupil and neural activation

Neuroscience; Behavioral neuroscience; Molecular neuroscience