A rat raised in an enriched environment grows a different cerebral cortex, a landmark study shows
How many toys sit in a rat's cage, and how varied they are, isn't just a matter of comfort: a landmark study measured its effect all the way down to the structure of the brain. Find our enrichment guidance in the rodent toys and enrichment section.
A landmark study on enriched environments
Diamond, Krech, and Rosenzweig published a study comparing the histology of the cerebral cortex in rats raised in an enriched environment versus an impoverished one in the Journal of Comparative Neurology in 1964 (research on Google Scholar). The researchers measured a significantly thicker cerebral cortex in rats raised with varied toys, companions, and regularly changed layouts, compared with those raised alone in a bare cage — one of the very first demonstrations that environment reshapes the brain's physical structure, not just behaviour.
What this means for setting up the cage
This study, now a classic in neuroscience, backs up a simple principle applied to pet rat cages ever since: regular environmental stimulation isn't a luxury but a measurable factor in brain development.
- Rotate toys and layouts regularly rather than leaving the same setup unchanged for months.
- Add plenty of surfaces to explore: tubes, bridges, platforms, and objects to manipulate stimulate different aspects of behaviour.
- Never house a rat alone long-term: the presence of companions was part of the enrichment measured in the study, just as much as the objects.
This enrichment guidance rounds out the profile covered in the fancy rat profile. Our page on fancy rat enrichment offers practical rotation ideas.
Frequently asked questions
Has this effect on the brain been confirmed since 1964?
Yes, many later neuroscience studies have confirmed and refined these results, making environmental enrichment a well-established principle in rats as in other species.
Do I need to change every toy every week?
A partial, regular rotation is enough; the main point is avoiding a setup that stays identical for months with no novelty at all.
Does an adult rat still benefit from this enrichment, or only young ones?
The benefits carry into adulthood, though the measured effects are often stronger in young, still-developing animals. Find all our guides on the rodent hub.
This guide is part of Planète Pets’s Rodents universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.