Influence of environmental enrichment on rodents' brains: neurochemical and neuroanatomical aspects

Abstract

Housing laboratory rodents in complex and enriched environments increases their exposure to physical, sensorial, social, and cognitive stimuli. Exposure to enriched conditions has been associated with animals having an optimized response to cope with challenges. This is related to improvements in cognitive functions, including memory and learning, processes that are modulated by the monoaminergic system. Dopamine, serotonin, and norepinephrine participate in several functions, including alertness, motivation, arousal, motor control, emotional regulation, and neuronal plasticity. Environmental conditions influence their concentration in different brain regions, and research has shown that environmental enrichment improves the monoaminergic system regulation. Furthermore, neurochemical adaptations are also accompanied by changes in brain structure, as well as promoting neurogenesis and enhancing synaptic activity. This review presents an overview of the studies addressing the effect that environmental enrichment has on the neurochemistry and neuroanatomy of laboratory rats and mice. It will focus on the monoaminergic system to summarize the changes that enriched conditions elicit in dopamine, serotonin, and norepinephrine concentrations in different brain regions. Additionally, it will discuss some neuroanatomical aspects and differences in the electrical brain activity in laboratory rodents housed in enriched conditions.