Sleep is well-known to help us better understand what we have learned. But now, researchers believe they have discovered exactly how sleep helps our brains to better learn specific motor tasks, such as typing or playing the piano.
The study, published in the Journal of Neuroscience, is the first to use three different brain scans in order to determine changes in particular brainwaves and the exact location of changed brain activity in specific motor learning subjects.
Researchers carried out an analysis of 15 subjects who volunteered for motor learning experiments, which involved a series of finger-tapping tasks.
For the first 3 nights, the participants slept at whatever time they wanted to.
During this period, their brains were scanned using magnetoencephalography (MEG). This measured oscillations in the brain - rhythmic neural activity in the central nervous system - as well as polysomnography (PSG), which is tracking of the sleep phase.
The study authors say that by the end of the 3 nights, they had good baseline measurements of brain activity, and the participants had become used to sleeping in their surroundings.
Finger tapping tasks
The participants were then required to carry out a series of finger-tapping tasks on their "non-dominant" hand, in order to make it harder to learn.
Nine of the participants then slept for 3 hours, while the other six stayed awake. All participants were then scanned again with MEG and PSG.
One hour later, all participants were asked to perform the finger-tapping task. The results of this experiment showed that those who slept performed the task faster and more accurately compared with those who stayed awake.
Each participant was then scanned using magnetic resonance imaging (MRI) in order to see where the MEG oscillations they observed earlier were located in each individual's brain.
The findings revealed five different oscillations over eight different brain regions - four on each side of the brain.
The researchers expected the most significant activity to take place in the M1 region of the brain - the area responsible for motor control.
However, significant changes were instead discovered in the SMA (supplementary motor area) - a region in the top-middle of the brain.
The researchers then used caps of EEG sensors to further monitor brainwave changes in the participants. They found that the brainwave changes occurred during a specific phase of sleep called "slow-wave" sleep.
The study showed that two specific brainwave oscillations were identified in the SMA that play a part in the "reorganization" the brain carries out during sleep, in order to encourage motor learning.
"Delta" oscillations appeared to control changes in the connectivity of the SMA, while "fast-sigma" oscillations seemed to be related to changes in the SMA itself.
Further studies to incorporate visual tasks
These findings support the two criteria set at the beginning of the study, the researchers say. The delta and fast-sigma oscillations changed substantially after the subjects were trained in the finger-tapping tasks, and the strength of that change was linked to how much the participant's performance improved on each task.
The study authors say they have already started a new study to further understand how the brain consolidates the learning of visual tasks. They add that they would like to see whether similar frequency bands would be uncovered along with a similar organization of brain areas.