Ironically, some of our most stubborn habits and disorders are products of our plasticity.

If you want to lift a hundred pounds, you don't expect to succeed the first time. You start with a lighter weight and work up little by little. You actually fail to life a hundred pounds, every day, until the day you succeed. But it is in the days when you are exerting yourself that the growth is occurring.

Not all activities are equal in this regard. Those that involve genuine concentration—studying a musical instrument, playing board games, reading, and dancing—are associated with a lower risk for dementia. Dancing, which requires learning new moves, is both physically and mentally challenging and requires much concentration. Less intense activities, such as bowling, babysitting, and golfing, are not associated with a reduced incidence of Alzheimer’s. (254)

Nothing speeds brain atrophy more than being immobilized in the same environment.

We must be learning if we are to feel fully alive, and when life, or love, becomes too predictable and it seems like there is little left to learn, we become restless - a protest, perhaps, of the plastic brain when it can no longer perform its essential task.

Language development, for instance, has a critical period that begins in infancy and ends between eight years and puberty. After this critical period closes, a person’s ability to learn a second language without an accent is limited. In fact, second languages learned after the critical period are not processed in the same part of the brain as is the native tongue.

Psychoanalysis is often about turning our ghosts into ancestors, even for patients who have not lost loved ones to death. We are often haunted by important relationships from the past that influence us unconsciously in the present. As we work them through, they go from haunting us to becoming simply part of our history. (243)