To remember a phone number or an address, you hold the information in your mind for a few seconds until you have the chance to write it down. During this process, neurons in your brain fire coordinated electrical bursts, generating electrical waves that allow you to hold on to this information for as long as it is needed. This temporary storage of information is called working memory.
Scientists believe that when we use this type of memory, neurons in different areas of the brain communicate through synchronized bursts of activity. "Cells that fire together, wire together," says Robert Reinhart, a neuroscientist at Boston University.
As we age, working memory fades because distant brain areas no longer fire in sync. Prior studies demonstrated that reduced working memory in elderly people is related to uncoupled activity in separate brain areas. Reinhart and colleagues sought out to test whether recoupling brain waves in older adults would restore their working memory ability.
In a new study published in the journal Nature Neuroscience, Reinhart and his team used jolts of weak electrical stimulation applied to the scalp to synchronize waves in the prefrontal and temporal cortex - two brain areas involved in memory and cognition. They applied this current to 42 healthy people in their 60s and 70s. Before brain zapping, subjects looked at a series of images, some identical to one another and others slightly altered, and the objective was to spot whether the two images were different.
Then, participants took the test again, but this time while their brains were zapped with a current. After about 25 minutes of stimulation, participants were more accurate at identifying changes in the images compared to prior to the stimulation; their working memory was boosted.
A researcher tests transcranial stimulation on a research participant.
Photo source: NPR, Robert Reinhart
"In terms of this working memory task, we made the brain of a 70-year-old look like that of a 20-year-old," says Reinhart. But whether brain stimulation could boost the cognitive abilities of the elderly or help improve the memory of people with brain diseases such as Alzheimer's is unknown.
In the study, the working memory improvement lasted for just ~50 minutes and researchers did not measure any long-term effects of the stimulation treatment. Reinhart suspects that the cognitive boost may last for longer. The brain stimulation method used in this study is safe and non-invasive. Thus, these findings may contribute to more accessible treatments for cognitive decline in the elderly.