Ideal homes? Housing effects on rodent brain and behaviour.

Rodents used in biomedical research are typically reared in small cages that lack key features of their natural habitats. These conditions impose constraints on behaviour and brain development, resulting in altered brain functions. In this article, evidence for three different ways in which barren housing conditions interfere with brain development and behaviour is reviewed. Early environmental deprivation, thwarting of behavioral response rules, and disruption of habitat-dependent adaptation processes are shown to result in aberrant or maladaptive brain functions. Current standard housing conditions could therefore compromise the utility of rodents for research, especially in behavioural neuroscience. However, a better understanding of the animals' needs and of the environmental factors involved in the control of behaviour could offer a biological basis for refinement.