Developmentally stable sex-dependent modulation of turning asymmetry by neonatal novelty exposure

In rats, early life stimulation can enhance learning and memory and induce parallel changes in brain asymmetry. Despite persistent interest in human brain asymmetry, relatively little is known in animal models about developmental stability of early-experience effects on asymmetry and how early-experience may affect males and females differently in asymmetry measures across developmental stages. We exposed male and female neonatal rats to a novel cage for 3min per day during the first 3 weeks of life and measured spontaneous turning behavior at juvenility (7 weeks of age) and adulthood (7 months of age). We found that (1) the effects of such neonatal novelty exposure on turning bias are developmentally stable, and (2) neonatal novelty exposure differentially modulates turning bias in males and females. We briefly discuss implications of these findings in terms of the role of brain asymmetry in modulating cognitive and emotional development.