Most of us accept eventual memory impairment as an unfortunate fact of life, but recent advances in brain stimulation, funded by the U.S. Department of Defense, could be changing all that. On Tuesday, scientists conducting research within the program reported in the journal Nature Communications that they’d found a way to electrically stimulate the brain to improve memory recall in a significant way.

The goal of the program is to ultimately treat people with neurological disorders like Parkinson’s disease and epilepsy, which affect many combat veterans living with the long-term effects of head trauma and post-traumatic stress disorder. The new paper, published Tuesday, is a major step in achieving those goals. The team of researchers, led by Youssef Ezzyat, Ph.D. of the University of Pennsylvania, found that directly stimulating a part of the brain called the lateral temporal cortex could help improve patients’ memory recall by as much as 15 percent.

Electric Brain
By stimulating the lateral temporal cortex, scientists found they could improve patients' memory recall by 15 percent.

In the study, the researchers recorded the brain activity of 25 volunteers who were participating in a clinical trial intended to treat drug-resistant epilepsy, a seizure disorder that can affect a person’s memory. The patients read a list of 12 words and were instructed to remember them. All the while, scientists monitored the patients’ brain activity via electrodes on the cortical surface of the brain as well as embedded in the brain.

Feeding this data to a machine-learning algorithm showed them when a patient’s brain was most likely not encoding the memories properly. Later, when patients were performing a memory task, the electrodes hooked up to their lateral temporal cortex, a part of the brain associated with memory and language processing, gave the patients a little zap of electricity to stimulate the region whenever it detected activity associated with encoding deficits.

The study’s authors report that this monitoring and responding process, known as closed-loop stimulation, improved patients’ memory recall by 15 percent. This new study rests on previous findings by Ezzyat’s team, which demonstrated the potential of closed-loop brain stimulation for improving memory encoding. This differs from open-loop stimulation in that it only fires up when a patient is showing the biomarkers that indicate encoding problems. The latest research builds on this intervention by identifying an anatomical target for brain stimulation.

Since, as Inverse previously reported, the National Institutes of Mental Health isn’t very interested in funding this kind of research, it looks like this project and others funded by the D.O.D. could be doctors’ best bet at perfecting treatments that involve direct brain stimulation.

Abstract: Memory failures are frustrating and often the result of ineffective encoding. One approach to improving memory outcomes is through direct modulation of brain activity with electrical stimulation. Previous efforts, however, have reported inconsistent effects when using open-loop stimulation and often target the hippocampus and medial temporal lobes. Here we use a closed-loop system to monitor and decode neural activity from direct brain recordings in humans. We apply targeted stimulation to lateral temporal cortex and report that this stimulation rescues periods of poor memory encoding. This system also improves later recall, revealing that the lateral temporal cortex is a reliable target for memory enhancement. Taken together, our results suggest that such systems may provide a therapeutic approach for treating memory dysfunction.

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