A neuroprosthesis that (partially) restores memory

Thanks to a brain implant, a “memory prosthesismemory has improved in twenty patients, some of them with brain damage, reports an American paper published in Frontiers in human neuroscience. The performance of this device capable of mimicking the activity of the brain during the encoding of a memory gives hope to the future development team to delay the onset of dementia.

The hippocampus, the first area of ​​the brain damaged in memory disorders

The main mode of memory loss in the early stages of Alzheimer’s disease is the loss of the ability to form new memories.”, explains the neuroscientist Robert Hampson, from the Wake Forest University School of Medicine (United States) and who led this new work. In question, the function of the hippocampus, the area of ​​the brain responsible for encoding new memories. Severely affected in Alzheimer’s disease, the hippocampus is also damaged in Parkinson’s disease, epilepsy, head trauma or stroke related to memory disorders and, in particular, the ability to form new memories. “Indeed, specific lesions of hippocampal cells mimic many of the features of these diseases.”, specifies the scientist.

Originally, the device developed by the scientists was intended to compensate for memory loss due to traumatic brain injuries sustained by military forces, as part of the US Defense Agency’s (DARPA) RAM project. Objective: to restore memory to combatants, allow them to return to service, or improve the quality of life for veterans. “DARPA asked us to specifically study whether the technique worked for memory loss related to traumatic brain injury or repeated concussions.says Robert Hampson.

Electrodes that mimic the electrical activity of the hippocampus

This technique referred to by the neuroscientist consists of reproducing the electrical impulses produced by the hippocampus during the encoding of a new memory by means of an electrode implanted in the brain. All 24 patients in the study have already had electrodes placed to study and treat their drug-resistant epilepsy, and some also suffered brain damage. Each subject looked at an image, which they then had to recognize between 15 and 90 minutes later -we then speak of long-term memory- among other similar ones. When they looked at the image for the first time, the electrodes activated. Connected to their own stimulator controlled by a model developed over the years, they reproduced the electrical signals naturally produced by the hippocampus when encoding new memories.

Up to 50% memory improvement

Results, “our structured stimulation of the hippocampus during encoding improves recall and recognition up to 90 minutes later.”says Robert Hampson enthusiastically. Better, the greater the preexisting memory deficit, the more effective the stimulation, with an improvement of up to 50% in some subjects. Therefore, stimulation of the hippocampus to facilitate memory encoding was more beneficial for brain-damaged epileptics than for others. A degree of success that Robert Hampson describes as “amazing”. “This is a profound improvement in restoring memory function..”

The scientist insists on the notion of restoration of the lost function, as opposed to an improvement that would exceed the normal capacities of the human being. “Our goal is to be able to stop the decline in memory function, to add quality of life and more productive years to patients with Alzheimer’s disease.”concludes Robert Hampson. And provide whatever supporting science you can.”repair faulty memory” in all individuals. Next step: determine the parameters that increase the chances of success of the system to apply it to as many people as possible.

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