Inspired by research that showed enrichment could spark the growth of new neurons, he provided the rodents with cardboard for making nests, brightly colored balls for play, and ladders and ropes to climb. Remarkably, the animals were much slower to develop symptoms of a Huntington-like disease than their counterparts in standard housing—the first demonstration that enrichment could significantly influence neurological disorders. - http://science.sciencemag.org/content/359/6376/624.full