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.
Subject(s)
Behavior, Animal , Hippocampus/embryology , Individuality , Neurogenesis , Neuronal Plasticity/genetics , Animals , Body Weight , Brain/anatomy & histology , Brain/embryology , Brain/physiology , Female , Hippocampus/anatomy & histology , Hippocampus/physiology , Male , Mice , Mice, Inbred C57BL , Mice, Inbred Strains , Models, Animal , Organ SizeABSTRACT
Neurodegenerative disorders such as Alzheimer's disease (AD) are increasingly threatening public health. Most animal models of AD consist of transgenic mice that are usually housed singly or in unisexual groups in small barren cages. Such restricted environments, however, prevent the mice from showing a variety of species-specific behaviors and consequently may constrain comprehensive behavioral phenotyping. On the other hand, allowing the animals to freely organize their lives in a spacious physically and socially enriched environment makes behavioral phenotyping laborious and time consuming. Radio frequency identification (RFID) using a network of antennae and small glass-coated transponders labeling each individual allows for gathering spatiotemporal information about a large number of individuals in parallel. The aim of this project was to use the RFID technique to facilitate the characterization of mice carrying a genetic disposition to develop AD-like pathology and of their wild-type conspecifics in a spacious seminaturalistic environment.
