Prosthetic implant in brain improves memory

By ELAINE CHIAO | April 5, 2018

Prosthetics is a focus area in biomedical engineering that has been constantly expanding. Recently, scientists came up with a novel way of incorporating a person’s prosthetic memory system into regulatory brain processes such as encoding and retrieving memories.

Robert Hampson, a professor of Physiology and Pharmacology at Wake Forest Baptist Medical Center as well as the lead author of the study, shared his excitement regarding the new discovery.

“This is the first time scientists have been able to identify a patient’s own brain cell code or pattern for memory and, in essence, ‘write in’ that code to make existing memory work better, an important first step in potentially restoring memory loss,” Hampson said, according to ScienceDaily.

In the study, the researchers chose their subjects from epileptic patients at Wake Forest Baptist. Using an electronic prosthetic system based on a multi-input multi-output (MIMO) mathematical model, researchers were able to track and even influence the patients’ neuronal firing patterns in the hippocampal region.

Episodic memory, or the ability to retain information relating to autobiographical events, is the aspect of memory that the researchers focused on investigating. This is because patients who suffer from Alzheimer’s disease, stroke and head injury often share a common symptom of losing their episodic memories.

In everyday life, episodic memories can be categorized as anything ranging from remembering what you ate for breakfast yesterday morning to remembering where you parked your car.

Researchers carried out the first part of the study as the patients completed a simple computerized memory task that tested how well they remembered an image after a short delay in the absence of the image. 

After examining the observed neuronal codes, Theodore Berger and Dong Song, two biomedical engineers at the University of Southern California (USC), created a MIMO-based code for each patients’ correct memory performance. Across the board, the patients’ performance indicated a 37 percent increase when compared to the baseline.

The researchers then turned to a second part of the study, which incorporated a similar image identification task. Similarly, participants in this study showed a 35 percent improvement in performance.

Therefore, with the implementation of this prosthetic memory system, subjects in the pilot study demonstrated an average of 35 to 37 percent increase in their short-term memory performance.

The pilot study, which was funded by the U.S. Defense Advanced Research Projects Agency (DARPA), was recently published in the Journal of Neural Engineering.

“We showed that we could tap into a patient’s own memory content, reinforce it and feed it back to the patient,” Hampson said. 

In essence, the researchers identified a possible way to retrieve the correct memory from a person’s neuronal firing patterns even if the person seems to no longer retain that memory on the surface. 

The firing of neurons can shed light on the correct pattern of memory formation, and by identifying these patterns, researchers can further stimulate the person’s brain with the correct memory formation process.

At the current stage of research, the research team is still trying to fully decode and improve an individual’s intrinsic memory skills. 

However, in the future, Hampson’s team aims to specialize in helping people recover specific memories as their overall memory begins to deteriorate.

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