“As the twig is bent, so is the tree inclined.” We have long believed that experience and stimulation in early life determines social and intellectual behavior. Indeed, Freud presented theories that personality is largely formed by the age of five. We have broadened our views since then but it is clear that the young brain is malleable, capable of neuroplasticity, based on experience, e.g., John Paul Scott, Early Experience And The Organization Of Behavior way back in 1968.
What about the effects of enrichment on the brain? Rosensweig, Bennet and Diamond performed their classic experiments with rats back in the early 70s. Animals were raised in either a standard, “impoverished,” environment or an “enriched” environment that provided objects to explore and interact with. The brains of enriched rats were thicker and denser than those of impoverished rats. Hence, circumstances in the environment determine brain complexity and we now have programs such as Head Start for the young.
But when it came to the old, the belief was quite different. Whereas early experience had a primacy the old brain was described as declining and not thought to be capable of neuroplasticity. “You can’t teach an old dog new tricks.” Fortunately, we are breaking out of this dogma but old stereotypes are hard to change. The most recent evidence comes from a European study that demonstrated that an enriched environment directly impacts the hippocampus. The hippocampus is a critical brain circuit regulating the formulation of new memories and regulation of emotions. As an aging man with a shrinking hippocampus, I need to take this to heart.
The study demonstrated that enriching the environment produced new innervation within the hippocampus as well as establishing distant connections to other brain regions. The effect persisted even after the enrichment was no longer present. Furthermore, exercise also increases hippocampal neurons. These effects probably don’t alter the course of dementia but they have important implications for the changes in cognition that go with aging.
Finally, naps are beneficial to the brain and learning. Volunteers learned word pairings. Half watched a DVD after learning, half took a nap. The group that took a nap recalled the pairings five times better than those who watched the DVD. In short, the nap reduced forgetting. Brain activity in the hippocampus was thought to explain this effect.
So you can teach an old dog new tricks. As we have known for some time, the best way to deal with the changes of aging are to stay stimulated by enriching activities (e.g., hobbies, reading, beautifying home and garden, getting out into nature, meeting people, engaging in art/music, and studying things of interest). Exercise regularly. And take a nap after learning. Your hippocampus will love it.