Human Trials Begin on Memory-Improving Brain Implants

Researchers developing brain implants that could improve long-term memory have begun human trials, Nature reported.

According to evidence presented at the Society for Neuroscience meeting in Chicago in October, two studies funded by the U.S. military's research wing suggest that implanted electrodes could improve memory.

One of the projects—run by the University of Southern California (USC)—involves using electrodes to mimic the process of electrical stimulation in healthy brains through which long-term memories are formed.

USC biomedical engineer Dong Song said that the method had been tested on a female subject with epilepsy, who already had electrodes implanted in her brain. Song said it was too soon to say if the subject's long-term memory had improved, but that the team planned to carry out further human trials in the coming months.

The research was originally aimed at helping soldiers suffering from brain injuries, which are a common result of the detonation of Improvised Explosive Devices (IEDs.) According to the Brain Trauma Foundation, up to 300,000 veterans of the Iraq war may be suffering from some level of traumatic brain injury, many of which are undiagnosed.

However, the studies could also have implications for stroke victims and even those suffering memory loss through the normal aging process. Both studies worked with epileptic subjects who already had electrode implants in their brains.

Memory formation is complex and not fully understood, but the hippocampus—a structure in the brain thought to also play a role in emotion—is believed to be central to the process. In short-term memory, the hippocampus is thought to collect sensory information and hold it in a readily accessible format. Recalling this information regularly helps solidify it into the long-term memory. The process by which long-term memories are formed involves an electrical signal traveling from one part of the hippocampus (CA3) to another (CA1).

The USC study involved 12 subjects with epilepsy, who were asked to recall pictures 90 seconds after looking at them. Researchers mapped the pattern of electrical signals fired between CA3 and CA1 and used this to develop an algorithm that mimics the natural signaling pattern in healthy brains. The algorithm was accurate 80 percent of the time and would allow for the stimulation of CA1 cells in subjects whose CA3 cells were not firing properly—in other words, those with long-term memory damage.

The second study, carried out by neuroscientists at the University of Pennsylvania, recorded brain activity in 28 epileptic subjects while the subjects recalled a list of words. Using this information, the researchers produced an algorithm that could predict whether a person would forget a given word. By limiting electrical stimulation of the brain only to words likely to be forgotten, researchers hypothesized that memory performance could be improved by 140 percent.