A team of scientists from Wake Forest University School of Medicine and the University of Southern California (USC) have demonstrated the primary successful use of a neural prosthetic device to recall specific memories.
The findings appear online in Frontiers in Computational Neuroscience.
This groundbreaking research was derived from the Wake Forest and USC team’s 2018 study led by Robert Hampson, Ph.D., professor of regenerative medicine, translational neuroscience and neurology at Wake Forest University School of Medicine, that showed the successful implementation of a prosthetic system that uses an individual’s own memory patterns to facilitate the brain’s ability to encode and recall memory.
Within the previous study, the team’s electronic prosthetic system was based on a multi-input multi-output (MIMO) nonlinear mathematical model, and the researchers influenced the firing patterns of multiple neurons within the hippocampus, an element of the brain involved in making latest memories.
On this study, researchers built a brand new model of processes that assists the hippocampus in helping people remember specific information. When the brain tries to store or recall information similar to, “I turned off the stove” or “Where did I put my automobile keys?” groups of cells work together in neural ensembles that activate in order that the data is stored or recalled. Using recordings of the activity of those brain cells, the researchers created a memory decoding model (MDM) which allow them to decode what neural activity is used to store different pieces of specific information. The neural activity decoded by the MDM was then used to create a pattern, or code, which was used to use neurostimulation to the hippocampus when the brain was attempting to store that information.
“Here, we not only highlight an revolutionary technique for neurostimulation to boost memory, but we also exhibit that stimulating memory is not just limited to a general approach but can be applied to specific information that’s critical to an individual,” said Brent Roeder, Ph.D., a research fellow within the department of translational neuroscience at Wake Forest University School of Medicine and the study’s corresponding creator.
The team enrolled 14 adults with epilepsy who were participating in a diagnostic brain-mapping procedure that used surgically implanted electrodes placed in various parts of the brain to pinpoint the origin of their seizures. Participants underwent all surgical procedures, post-operative monitoring and neurocognitive testing at considered one of the three sites participating on this study including Atrium Health Wake Forest Baptist Medical Center, Keck Hospital of USC in Los Angeles and Rancho Los Amigo National Rehabilitation Center in Downey, California.
The team delivered MDM electrical stimulation during visual recognition memory tasks to see if the stimulation could help people remember images higher. They found that once they used this electrical stimulation, there have been significant changes in how well people remembered things. In about 22% of cases, there was a noticeable difference in performance.
Once they looked specifically at participants with impaired memory function, who got the stimulation on each side of their brain, almost 40% of them showed significant changes in memory performance.
“Our goal is to create an intervention that may restore memory function that is lost due to Alzheimer’s disease, stroke or head injury,” Roeder said. “We found probably the most pronounced change occurred in individuals who had impaired memory.”
Roeder said he hopes the technology may be refined to assist people live independently by helping them recall critical information similar to whether medication has been taken or whether a door is locked.
“While way more research is required, we all know that MDM-based stimulation has the potential for use to significantly modify memory,” Roeder said.
This research is built on greater than 20 years of preclinical research on memory codes led by Sam Deadwyler, Ph.D., emeritus professor of physiology and pharmacology at Wake Forest University School of Medicine, together with Hampson (now a member of the Wake Forest Institute of Regenerative Medicine), and the USC team led by biomedical engineers Theodore Berger, Ph.D., and Dong Song, Ph.D.
The preclinical work applied the identical form of stimulation to revive and facilitate memory in animal models using the MIMO system, which was developed at USC.
The research was funded by the U.S. Defense Advanced Research Projects Agency (DARPA).
