Differential impacts of social isolation and enriched environment on multi-sensory brain-wide functionality and network segregation.

Environmental factors profoundly affect the brain's sensory processing network, optimizing adaptive strategies for growth and survival. We hypothesized that sensory-specific functional responses and/or functional networks could be altered by manipulating environmental conditions. To elucidate how the environment influences brain development, we exposed male mice to two - socially isolated and enriched environments - during early life (from 4 to 11 weeks) and investigated their effects on mouse brain functionality using sensory stimulus-evoked BOLD fMRI and resting-state fMRI. Here, we show that social isolation leads to reduced segregation of brain networks, notably affecting the olfactory and visual networks. Conversely, the enriched environment maintains network segregation while enhancing higher order sensory and visual cortical functions. Additionally, enriched mice exhibited an improved sensorimotor functional response. Our combined use of sensory stimulus-evoked BOLD fMRI and resting-state fMRI revealed changes at local and global levels, providing a comprehensive perspective. This expands our understanding of how environmental factors influence brain functionality and highlights the importance of physical and social cues - such as tactile, visual, and olfactory - that may provide therapeutic insights for psychiatric disorders.