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

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.

The brain is a far more open system than we ever imagined, and nature has gone very far to help us perceive and take in the world around us. It has given us a brain that survives in a changing world by changing itself.

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

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.

All of us have worries. We worry because we are intelligent beings. Intelligence predicts, that is its essence; the same intelligence that allows us to plan, hope, imagine, and hypothesize also allows us to worry and anticipate negative outcomes.

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