Sleep strengthens motor learning through targeted brain rhythms

When faced with difficult tasks, sometimes people hit a mental wall and make the decision to "sleep on it." Returning to the task after sleeping, they often perform better. Why? Rhythmic brain activity during sleep transforms task-related information into stronger, longer-term memory. A new JNeurosci paper on research led by Dara Manoach, from Harvard Medical School, advances understanding of where in the brain this rhythmic activity appears to improve motor learning. 

In the study, 25 participants learned a typing sequence while the researchers recorded their brain activity. After training, brain recordings continued as study participants napped. During sleep, cortical brain areas active during training had more rhythmic activity. Increased brain rhythms in these areas correlated with how much participants improved in the task after the nap. Notably, pre- and postnap task performance had different neural correlates; learning during training was associated with increased brain rhythms in movement execution areas during sleep, while postnap performance was linked to increased brain rhythms in movement planning areas during sleep. Says Manoach, "Brain rhythms occur everywhere in the brain during sleep. But the rhythms in these regions increase after learning, presumably to stabilize and enhance memory." 

The researchers theorize from their work that brain rhythms in motor execution areas may represent the memory of a task, while the rhythms in motor planning areas improve future performance.