Emergence of Individuality in Genetically Identical Mice

TLDR

Brain plasticity as a neurobiological reflection of individuality is difficult to capture in animal models. The study introduces a paradigm to serve as an animal model for identifying mechanisms of plasticity underlying nonshared environmental contributions to individual differences in behavior. The authors used a twin‑study–inspired paradigm, collecting dense longitudinal activity data from 40 inbred mice housed together in a large enriched environment to model plasticity mechanisms. Exploratory activity diverged over time, increasing individual differences with age; cumulative roaming entropy correlated positively with adult hippocampal neurogenesis, indicating that developmental factors contribute to individual differences in brain plasticity and behavior.

Abstract

Brain plasticity as a neurobiological reflection of individuality is difficult to capture in animal models. Inspired by behavioral-genetic investigations of human monozygotic twins reared together, we obtained dense longitudinal activity data on 40 inbred mice living in one large enriched environment. The exploratory activity of the mice diverged over time, resulting in increasing individual differences with advancing age. Individual differences in cumulative roaming entropy, indicating the active coverage of territory, correlated positively with individual differences in adult hippocampal neurogenesis. Our results show that factors unfolding or emerging during development contribute to individual differences in structural brain plasticity and behavior. The paradigm introduced here serves as an animal model for identifying mechanisms of plasticity underlying nonshared environmental contributions to individual differences in behavior.