Critical Periods

Some learning runs on a deadline. During critical periods, the young brain is unusually open to certain inputs, and the window can close hard. Language is the classic case: children who pick up a second language early usually reach native-level fluency and a flawless accent, while most adults who start later keep a trace of one no matter how fluent they become.

But the adult brain is far from frozen. People who take up an instrument in their twenties or later still show measurable changes in motor and auditory brain regions as they practice. Learning new things as an adult simply takes more deliberate repetition than it did in childhood. The wiring still moves; you just have to push it harder and more often.