A good night's sleep may feel restful for the body, but it can be hard work for the brain.
A new study shows that after spending evening hours learning a new skill, regions of the brain associated with learning work overtime to assimilate the lessons while we sleep, and we awaken with the new skills entrenched.
The researchers, led by Giullo Tononi, a neuroscientist at the University if Wisconsin-Madison, asked a group of 12 subjects to play a simple computer game that involved moving a cursor around the screen to various, specified positions. The subjects played the game before going to sleep.
During some sessions (and unbeknownst to the players) the cursor's path was altered, putting players into a task-learning scenario by forcing them to adjust their style of play to adapt to the handicap.
After the game, 256 electrodes were taped to the subjects' heads and used to measure their electrical brain activity during slumber.
Those who played the altered version of the game – the one involving learning – showed a surge of brain activity in a penny-sized region of the right hemisphere of the brain.
Subjects who played the straight version of the game did not exhibit this effect.
During sleep, the brain's nerve cells synchronize their firing to produce a pattern known as slow-wave activity (SWA), which is characterized by long periods of deep sleep, alternating with short bursts of rapid eye movement during which, it is believed, we dream.
Subjects in the study who were forced to struggle with the altered version of the game had increased SWA on six of the 256 electrodes clustered around the posterior parietal cortex in the brain's top right hemisphere.
This region is thought to be important in visual attention and spatial processing, as well as controlling hand-eye co-ordination during waking hours.
What's more, subjects who showed boosted brain activity during sleep as a result of learning the new task performed better at the game in the morning.
"The amazing thing is when you compare different people, the ones who had the most initial trouble controlling the cursor, and who therefore worked the hardest at the learning task showed the greatest local SWA increases," Dr. Tononi said.
