Practice makes perfect. To become ambidextrous in basketball, dribble with your left hand, switch to your right, and repeat the process again and again. Likewise, to solve differential equations in math, pile them up and work your way through them diligently.
According to one popular school of thought, it’s this active, repeated manipulation of material that lays the neural foundations for skill development. All too often, time away from the basketball court—or the math books—is seen as a break in the learning process, a way to cool off, reenergize, and then return to the vital work of actual practice.
But for Leonardo Cohen, a neuroscientist at the National Institutes of Health and the senior author of a June 2021 study published in the journal Cell, the idea that breaks are a cooling-off period is a misconception.
Cohen and his colleagues used magnetoencephalography—a highly sensitive brain-scanning technique—to observe the neural activity of young adults as they learned how to type with their nondominant hand. After a practice session, the study participants were given a short break and then continued practicing for a total of 35 sessions.
When analyzing the data, Cohen’s team made an intriguing discovery: They observed a spike in brain activity, mimicking the neural pattern seen during the practice session, but compressed by twentyfold. Rather than being idle, the brain was replaying the practice session over and over at an astonishingly high rate of speed—flipping the material from the neocortex, where sensory and motor skills are processed, to the hippocampus, the brain’s memory center, over two dozen times in the span of 10 seconds. Stepping away from the activity, it turns out, is not stepping away from the activity at all.
The findings echo the groundbreaking discovery in 2001 that after successfully running through a maze, rats replayed those memories repeatedly during REM sleep, with the same spatial circuitry flickering to life as they slept.