By using sound, parts of the brain can impact and increase working memory, the system that allows people to remember and manipulate information in the presence of additional incoming information. Such manipulation could possibly help people who suffer from mild cognitive impairment.
Christine Beauchene is studying how working memory is impacted through the use of binaural beats and how development of the technology could result in a portable, easy-to-use, closed-loop therapeutic system.
Beauchene’s work, "EEG-based control of working memory maintenance using closed-loop binaural stimulation," has been published in PLOS-One and the Journal of Neural Engineering. By delivering two pure tones independently to each ear with a small frequency mismatch, Beauchene found that binaural beats can affect synchronization in the brain and boost working memory capacity.
“If we play 240Hz into the right ear and 255Hz into the left ear, we can see an increase in the measured brain recordings at the difference of the two tones of 15Hz,” said Beauchene, a mechanical engineering doctoral student in the College of Engineering. “Using this method, we can safely and noninvasively stimulate the brain at a desired frequency."
Working memory capacity depends on front and upper back parts of the brain being in synch. Higher synchronization means people will, on average, respond with higher accuracy during a working memory task.
Currently, nearly all therapeutic stimulation systems are “one-size-fits-all” approaches. However, because each person's brain responds differently to external stimuli and can change over time, these approaches may not be as effective. The driving motivation for developing a closed-loop stimulation system is to help people with mild cognitive impairment (MCI).
In this study, people with MCI are the focus because working memory is one of the earliest cognitive functions to show significant decline as they age. If working memory can be boosted, then quality of life in patient's with this impairment can be further improved.
Beauchene is working to develop an experimental system to tailor the frequency of the binaural beat stimulus to each person using closed-loop control.
“Cognitive function naturally decreases with time,” explained Beauchene. “In people with MCI we see a larger decrease earlier than you’d normally expect in healthy adults.”
Beauchene is quick to point out that because someone has MCI doesn’t mean they will end up with Alzheimer’s or dementia, but the odds increase.
Before this research, no one had studied the effects of binaural beats on working memory and correlated the changes seen in behavior to the changes in the brain connectivity graphs.
“We have found really interesting and similar results between two different working memory tasks,” said Beauchene. “While listening to 15Hz binaural beats, during both tasks, we found about a 3 percent increase in participant response accuracy on average.”
The increase, while not dramatic, is close to the range of cognitive decrease found within MCI patients, and therefore could be a viable therapeutic method. Of the frequencies Beauchene has tested, 15Hz is the only binaural beat frequency that produces the strong frontal/parietal connection that will help augment working memory capacity.
For now, Beauchene plans to defend her thesis in 2018 and build upon her undergraduate biomechanics studies to develop better therapeutic options for people suffering from memory loss.
Beauchene’s academic advisors are Alexander Leonessa, associate professor of mechanical engineering, and Nicole Abaid, assistant professor of biomedical engineering and mechanics.
Written by Rosaire Bushey