The aging brain can learn and grow.  This new conventional wisdom—based on the latest neurophysiological research—replaces the old conventional wisdom (which was that the brain has only a fixed number a cells set at birth and that older people cannot learn with the flexibility of younger people).

So much for conventional wisdom of any kind.  Once, during an illness, one of my doctors gave me a 500 page book on “Psychopharmocology”—a technical text on the effects of drugs on the brain.  I read it as best I could—it was quite technical—and returned it to my doctor.

“Interesting!” I said, “what I could understand of it.  Why did you have me read it?”

My doctor replied, “So you could see how little we know.”

When I was in rehabilitation for a brain infection, my doctor there told me about the latest research concerning mice and learning.  If you make a mouse run a maze to get some cheese, they will over time learn to run it faster.  However, if you make a mouse swim in water too deep for it to stand to get the cheese, it will learn three to four times faster.  According to my doctor, these results had had revolutionized the way her profession treated people with brain injury.  Putting the patient under some stress made their recovery faster.

We now know that the brain retains the ability to regenerate and grow new neural circuits throughout life, and even into old age.  This has implications for the spiritual life.  While it is true that intense spiritual practices designed for youth (primarily young men) — long retreats, monastic practice, asceticism, and so on – are not so practical as we grow older, there are other kinds of practices that are more suitable for maturity than youth.  Among these are meditations on impermanence, loving kindness, and gratitude.  In some basic sense it takes a whole life to appreciate a whole life.

Here is another story about the plasticity of the brain.  I have a good friend, a psychiatrist, who is 79.  He took up studying the piano in his 70s.  He loves to play—especially to improvise—and though it is hard for him to learn the theory and technique of the piano, he keeps at it.

“It makes me tired,” he said, “all the music theory and technical details.”  He gestured to me, knowing that I have been playing piano all my life.  “It must be so easy to start when you’re young.”

I acknowledged that that was so, but also suggested that perhaps he was tired because his brain was busy growing neurons to accommodate his new art.  “That’s a good thing,” I said.  “It’ll make you live longer.”

He liked hearing that.