External stimulation during sleep enhances the acquisition of a skill, new research from Northwestern University shows. In the case of the research, the playing of a musical piece during the test subjects’ sleep allowed them to learn the piece faster than an unplayed one.
The new research expands on existing evidence suggesting that “memories can be reactivated during sleep and storage of them can be strengthened in the process.”
For the study, research test subjects “learned how to play two artificially generated musical tunes with well-timed key presses.” Then, while taking a 90-minute nap, one of the tunes that had been practiced was played, but not the other one.
“Our results extend prior research by showing that external stimulation during sleep can influence a complex skill,” said Ken A. Paller, professor of psychology in the Weinberg College of Arts and Sciences at Northwestern and senior author of the study.
The researchers used EEG methods to study the brain’s electrical activity, they did this to ensure that the musical cues were played during slow-wave sleep, which is a stage of sleep that has been linked to cementing memories in previous studies. The test subjects made fewer errors when recreating the melody that had been played while they were sleeping, when compared to the melody that hadn’t been played.
“We also found that electrophysiological signals during sleep correlated with the extent to which memory improved,” said lead author James Antony of the Interdepartmental Neuroscience Program at Northwestern. “These signals may thus be measuring the brain events that produce memory improvement during sleep.”
“The age-old myth that you can learn a foreign language while you sleep is sure to come to mind,” said Paul J. Reber, associate professor of psychology at Northwestern and a co-author of the study.
“The critical difference is that our research shows that memory is strengthened for something you’ve already learned,” Reber said. “Rather than learning something new in your sleep, we’re talking about enhancing an existing memory by re-activating information recently acquired.”
The next step, the researchers say, is to find out what other types of learning this method can be applied to.
“If you were learning how to speak in a foreign language during the day, for example, and then tried to reactivate those memories during sleep, perhaps you might enhance your learning.”
This research may also give insight into the basic mechanisms in the brain that are activated during sleep to help preserve ‘memory’.
“These same mechanisms may not only allow an abundance of memories to be maintained throughout a lifetime, but they may also allow memory storage to be enriched through the generation of novel connections among memories,” he said.
The door is open “for future studies of sleep-based memory processing for many different types of motor skills, habits and behavioral dispositions,” Paller said.