Sleep is crucial for helping your brain to catalogue what you’ve learned that day. But for millions of people with neurological disorders, the processes required to consolidate information simply don’t work properly.
Now, scientists have discovered an unusual method that could help improve the memories of people with conditions such as autism, Alzheimer’s disease, schizophrenia and major depressive disorder.
Researchers at the University of North Carolina used weak electric currents to target a specific area in the brains of sleeping volunteers. The non-invasive method strengthened memory in the participants, the study found.
Scientists have, for years, tried to understand how electrical brain activity generated during sleep affects memory. It has long been suspected that the so-called sleep spindles play a part.
“But we didn’t know if sleep spindles enable or even cause memories to be stored and consolidated,” said senior author Flavio Frohlich.
“They could’ve been merely byproducts of other brain processes that enabled what we learn to be stored as a memory. But our study shows that, indeed, the spindles are crucial for the process of creating memories we need for every-day life. And we can target them to enhance memory.”
Frohlic’s study represents the first time researchers have targeted sleep spindles without also increasing other natural electrical brain activity.
During the trial, 16 healthy male participants were tasked with performing two common memory exercises before they went to sleep.
The first involved associative word-pairing, while the second was a motor sequence tapping task. Half the group received a real transcranial alternating current stimulation (TACS), while the other half received a placebo.
The next morning, participants had to perform the same memory tests. There was no improvement in the word test scores of those who had received TACS, but there was a noted improvement when it came to performing the motor task.
“This demonstrated a direct causal link between the electric activity pattern of sleep spindles and the process of motor memory consolidation.” Frohlich said.
Caroline Lustenberger, PhD, first author and postdoctoral fellow in the Frohlich lab, said, “We’re excited about this because we know sleep spindles, along with memory formation, are impaired in a number of disorders, such as schizophrenia and Alzheimer’s. We hope that targeting these sleep spindles could be a new type of treatment for memory impairment and cognitive deficits.”
The findings were published in the journal Current Biology.