How Sleep Helps Brain Learn Motor Task

We have figured out that sleep is conducive to memory of waking status. When it comes to learning tasks, sleep also helps the brain consolidate what we’ve learned. However, it is not clear that what goes on in the brain to make that happen for different kinds of learned tasks. A new study shows the brainwave frequencies and brain region associated with sleep-enhanced learning of a sequential finger tapping task similar to typing, or playing piano.

In a sleep lab on Brown's campus researchers use now using caps of EEG sensors in studies of how the brain works to consolidate learning visual tasks. Here graduate student Aaron Berard models the cap.Specifically, the results of complex experiments performed at Massachusetts General Hospital and then analyzed at Brown show that the improved speed and accuracy volunteers showed on the task after a few hours sleep was significantly associated with changes in fast-sigma and delta brainwave oscillations in their supplementary motor area (SMA), a region on the top-middle of the brain. These specific brainwave changes in the SMA occurred during a particular phase of sleep known as "slow-wave" sleep.

Scientists have shown that sleep improves many kinds of learning, including the kind of sequential finger-tapping motor tasks addressed in the study, but they haven't been sure about why or how. It's an intensive activity for the brain to consolidate learning and so the brain may benefit from sleep perhaps because more energy is available or because distractions and new inputs are fewer, said study corresponding author Yuka Sasaki, a research associate professor in Brown's Department of Cognitive, Linguistic & Psychological Sciences.

"Sleep is not just a waste of time," Sasaki said.

The extent of reorganization that the brain accomplishes during sleep is suggested by the distinct roles the two brainwave oscillations appear to play. The authors wrote that the delta oscillations appeared to govern the changes in the SMA's connectivity with other areas of the cortex, while the fast-sigma oscillations appeared to pertain to changes within the SMA itself.