Scientists have successfully demonstrated the implementation of a prosthetic system that can use a patient’s own memory patterns to help the brain encode and recall memories.

In the pilot study of the technology, conducted by researchers from the Wake Forest Baptist Medical Center and the University of Southern California (USC), the short-term memory performance of participants showed a 35% to 37% improvement over baseline measurements.

The study’s lead author Robert Hampson, PhD, professor of physiology/pharmacology and neurology at Wake Forest Baptist, said: “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.”

The study aimed to improve episodic memory, the most common type of memory loss in people suffering from Alzheimer’s disease, stroke and head injury. Episodic memory is information that is new and useful for a short period of time, such as remembering a car parking space.

Firstly, the researchers recorded neural patterns or ‘codes’ of each participant while they performed a computerised memory task. This involved the patients viewing a simple image, such as a colour block, and then after briefly looking at a blank screen they were asked to identify the initial image out of four or five new images.

The study’s participants were selected from epilepsy patients at Wake Forest Baptist who were taking part in a diagnostic brain-mapping procedure that used surgically implanted electrodes placed in various parts of the brain to pinpoint the origin of the patients’ seizures.

The team used an electronic prosthetic system based on a multi-input multi-output (MIMO) nonlinear mathematical model to influence the firing patterns of multiple neurons in the hippocampus, the part of the brain involved in making new memories.

The USC team analysed the recordings and created a MIMO-based code for correct memory performance. Then the Wake Forest Baptist researchers played back that code through the patients’ prosthetic systems while they performed the image recall task. In this test, the patients’ episodic memory performance improved by 37% over baseline.

In a second test, participants viewed a highly distinctive image, followed by a short delay, and were then asked to identify the first photo out of four or five others. The memory trials were repeated with different images while the neural patterns were recorded during the testing process to identify and deliver correct-answer codes.

Participants were also shown sets of three pictures, including original and new photos, and were asked to identify the original photos, which had been seen up to 75 minutes earlier. When stimulated with the correct-answer codes, participants’ memory improved 35% over baseline.

In the future, the researchers hope they will be able to help patients who suffer from memory loss to hold on to their most important memories.

Chief scientific officer of Alzheimer’s Research UK Dr David Reynolds said:  “People with Alzheimer’s disease often have difficulty recalling recent events, even while still being able to remember things that happened decades earlier. Techniques that boost a person’s ability to lay down new memories could potentially help tackle one of the most common symptoms affecting people with dementia.

“By stimulating the pattern of brain electrical activity a person displays when successfully committing something to memory, researchers in this study were able to improve memory ability in a small group of people living with epilepsy.”

However, as none of the study participants suffered from dementia, Reynolds pointed out that it remains unclear whether this approach could benefit dementia patients.