# Affiliative behaviours regulate allostasis development and shape biobehavioural trajectories in horses

## TL;DR

This study shows that extended maternal presence in young horses boosts brain development and improves behavior and health.

## Contribution

The study reveals how prolonged maternal presence affects brain maturation and biobehavioural outcomes in horses.

## Key findings

- Prolonged maternal presence promotes maturation of brain regions linked to social behavior and physiological regulation.
- Offspring with extended maternal presence show higher default mode network connectivity and better social and feeding behaviors.
- Extended maternal presence correlates with higher concentrations of circulating lipids like triglycerides and cholesterol.

## Abstract

Social interactions shape both the physiological and behavioural development of offspring, and poor care/early caregiver loss is known to promote adverse outcomes during infancy in both animals and humans. How affiliative behaviours impact the future development of offspring remains an open question. Here, we used Equus caballus (domestic horse) as a model to investigate this question. By coupling magnetic resonance imaging, longitudinal biobehavioural assessments and advanced multivariate statistical modelling, we found that prolonged maternal presence during infancy promotes the maturation of brain regions involved in both social behaviour (anterior cingulate cortex and retrosplenial cortex) and physiological regulation (hypothalamus and amygdala). Additionally, offspring benefiting from a prolonged maternal presence showed higher default mode network connectivity, improved social competences and feeding behaviours, and higher concentrations of circulating lipids (triglyceride and cholesterol). The findings of the present study underscore the salient role of social interactions in the development of allostatic regulation in offspring.

The present study shows that maternal presence beyond early life remains crucial for brain, behavioural and physiological development in young horses, highlighting the importance of the mother–offspring relationship during a childhood-like stage.