The Contribution of Environmental Complexity to Phenotypic Variation in Mice and Rats

Abstract

The reproducibility and translation of neuroscience research is assumed to be undermined by introducing environmental complexity and heterogeneity. Rearing laboratory animals with minimal (if any) environmental stimulation is thought to control for biological variability but may not adequately test the robustness of our animal models. Standard laboratory housing is associated with reduced demonstrations of species typical behaviors and changes in neurophysiology that may impact the translation of research results. Moreover, modest increases in environmental enrichment (EE) mitigate against insults used to induce animal models of disease, directly calling into question the translatability of our work and may in part underlie the disconnect between preclinical and clinical research findings. Enhancing environmental stimulation for our model organisms promotes ethological natural behaviors but may simultaneously increase phenotypic trait variability. To test this assumption, we conducted a systematic review and evaluated coefficients of variation between EE and control housed animals. Overall, animals housed in enrichment were not more variable than controls. Therefore, environmental heterogeneity introduced into the laboratory does not compromise data integrity.