Our brains are at work even when we sleep. It is busy sorting and consolidating our day’s happening and storing information in our memory so that we can use it when need be. Memory impairment is debilitating for people suffering from neurological conditions – it affects their everyday life in several ways. The researchers at the UNC School of Medicine have for the first time used transcranial alternating current stimulation, or tACS, to target a specific kind of brain activity during sleep and strengthen memory. The findings of the study were published recently in the journal Current Biology.
This research offer a non-invasive way that has the potential to help millions of people suffering from conditions such as autism, Alzheimer’s disease, schizophrenia, and major depressive disorder. The electrical brain activity during sleep oscillates; they present as waves on an electroencephalogram and are called sleep spindles. Researchers have suspected the involvement of sleep spindles in cataloging and storing memories while we sleep.
Flavio Frohlich, PhD, assistant professor of psychiatry and member of the UNC Neuroscience Center remarked that it was not known for sure if sleep spindles enable or even cause memories to be stored and consolidated. It was also possible that they were merely byproducts of other brain processes that helped in storing what we learn as a memory. But, this study has shown evidence that the spindles are key to the process of creating memories we need for every-day life. Hence, they can be targeted to enhance memory. It is for the first time selective targeting of sleep spindles without increasing other natural electrical brain activity during sleep have been done by a research group. The same couldn’t be accomplished with tDCS – transcranial direct current stimulation – in which a constant stream of weak electrical current is applied to the scalp.
Frohlich’s team previously used tACS to target the brain’s natural alpha oscillations to boost creativity. This was a proof of concept. It showed it was possible to target these particular brain waves, which are prominent as we create ideas, daydream, or meditate. These waves are impaired in people with neurological and psychiatric illnesses, including depression The 16 male participants who volunteered for the study underwent a screening night of sleep before completing two nights of sleep for the study. The participants were made to perform two common memory exercises before going to sleep each night – these exercises were – associative word-pairing tests and motor sequence tapping tasks, which involved repeatedly finger-tapping a specific sequence. On the night of study, each participant had electrodes placed at specific spots on their scalps. During sleep on one night each person received tACS – an alternating current of weak electricity synchronized with the brain’s natural sleep spindles and the other night, each person received sham stimulation as placebo. On both the mornings the participants were made to perform the same memory tests. No improvement…