A study at the University of Pennsylvania has shown for the first time that memory function can be restored during a lapse by electrical stimulation. The team of neuroscientists led by Michael Kahana, professor of psychology, published its findings in the journal Current Biology.

The study revealed an important link between appropriately timed deep-brain stimulation and its potential therapeutic benefits. This is a key advancement for Restoring Active Memory, a four-year Department of Defense project created to develop next-generation technologies that improve memory function in people who suffer from memory loss. Dr. Kahana is lead principal investigator for the program.

The Penn team began by studying and decoding signal patterns that correspond to highs and lows of memory function.​​​“By applying machine-learning methods to electrical signals measured at widespread locations throughout the human brain, we are able to identify neural activity that indicates when a given patient will have lapses of memory encoding,” said Youssef Ezzyat, a senior data scientist in Dr. Kahana’s lab and lead paper author.

The team used this model to examine how the effects of stimulation differ during poor versus effective memory function. Participants included neurosurgical patients receiving treatment for epilepsy at the Hospital of the University of Pennsylvania as well as the Thomas Jefferson University Hospital, the Dartmouth-Hitchcock Medical Center, the Emory University Hospital, the University of Texas Southwestern, the Mayo Clinic, Columbia University, the National Institutes of Health Clinical Center and the University of Washington. Patients were asked to study and recall lists of common words while undergoing brain stimulation at safe levels. The researchers used electrodes implanted in the patients’ brains to record electrical activity and were able to identify the biomarkers of successful memory function, activity patterns that occur when the brain effectively creates new memories.

“We found that, when electrical stimulation arrives during periods of effective memory, memory worsens,” Dr. Kahana said. “But when the electrical stimulation arrives at times of poor function, memory is significantly improved.”

The findings could lead to advancements for patients with traumatic brain injury or neurological diseases, such as Alzheimer’s.

“Technology based on this type of stimulation could produce meaningful gains in memory performance, but more work is needed to move from proof-of-concept to an actual therapeutic platform,” said Daniel Rizzuto, director of cognitive neuromodulation at Penn.