Animal models show that ceasing movement or de-enriching the environment leads to nervous system atrophy, while enrichment and movement enhance neuronal size, connections, and potentially number.

“the best way to get a nervous system to atrophy, to lose neurons, shrink neurons, and or lose connections between neurons, is to stop that animal from moving. Or to de-enrich its environment, deprive it of some sensory input or multiple sensory inputs. And the best way to enhance the size of neurons, the number of connections between neurons, and maybe even the number of neurons, is to enrich its environment and get it moving while enriching that environment.”