Narrator: This is Science Today. A brain at any age benefits from enrichment. Marian Diamond, a professor and brain researcher at the University of California, Berkeley, says that's because dendrites - the branches on nerve cells - flourish with stimulation.

Diamond: When we stimulate a nerve cell, the branches grow just like the fingers unwinding from a folded hand and when we cut out the input to that nerve cell, you lose those branches.

Narrator: Diamond has studied the brains of rats for over 30 years and although the young benefit the most, rats of all ages grow these new branches when stimulated.

Diamond: Providing they were healthy, had good diets, had clean conditions and so forth and a minimum of stress as far as we know, we could stimulate the branches of the nerve cells which receive the stimuli that are coming in. These are the receptive surface, so the more branches that you have, the more options the nerve cell can take.

Narrator: For Science Today, I'm Larissa Branin.