"Neuroplasticity is one of science's most startling discoveries of the past thirty years.We used to think brain development was a one-way street: you were born with a thousand trillion neural connections, give or take, and what followed was mostly a lifetime of pruning, according to the rules of use it or lose it. We now know that the brain can retrofit itself, growing new neural connections(and pumping up existing ones) upon exposure to novel circumstances. That's what adaptation is all about.
Of course, Olga Kotelko, the subject of Grierson's book is not young, but the point he makes is that neuroplasticity is working even into one's 90s - at least into Olga's 90s - in a marvelous way. And I turned only 68 yesterday.