Most people claim to have an imperfect memory, one that they’d rather see improve somehow, perhaps through things like brain-training games. Researchers funded by the U.S. military have outlined a new technique designed to give your memory a boost that may seem a little extreme: The method delivers electrical shocks directly to the brain through implanted electrodes. The findings of the multiple studies were announced at the Society for Neuroscience meeting in Chicago, Illinois, at the end of October, and have been reported by Nature.
This research was inspired by soldiers who had suffered severe brain injuries during combat missions, impacting their ability to consolidate short-term memories into long-term memories. This consolidation takes place in the hippocampus, which is also associated with the regulation of stress and spatial navigation. Repeated accessing of specific short-term memories will reinforce the neural pathways associated with them, transforming them over time into long-term memories.
This reinforcement process sends an electrochemical signal from one part of the hippocampus, the CA3, to another, the CA1. If the signal is interrupted due to an injury to the hippocampus, then this consolidation process will occur far less frequently. The researchers behind this new invasive study thought that by recreating this signal, they might be able to restore the ability to consolidate memories.
Brain surgery is always fairly risky, so the researchers trialled their implant devices on epilepsy sufferers who already had implanted electrodes. In one of the studies presented, the team described how they asked 12 epileptics to observe a series of images and to recall up to 90 seconds later the images they had seen. Electrochemical firing was detected in both the CA3 and CA1 parts of the hippocampus as they did so.
The researchers then developed an algorithm – a piece of mathematical coding processed by a computer – based on these readings, which attempted to predict the signal pattern coming from the CA3 cells without directly detecting it. The algorithm correctly predicted the pattern 80% of the time.
This means that in the near future, electrodes implanted in the brain of those with damaged CA3 hippocampus regions could use this algorithm to electrically communicate with the CA1 cells in order to mimic an appropriate CA3 signal. This technique would effectively restore the memory consolidation process in humans, and although the results of any direct human trials have yet to be published, the same CA1 stimulation technique has been used on a group of monkeys and shown to be viable.
Image credit: the hippocampus region of the brain, highlighted. Shutterstock/decade3d - anatomy online.
“The data is convincing, but I’m still at a loss for understanding,” said Thomas McHugh, a neuroscientist at the RIKEN Brain Science Institute in Tokyo, as reported by Nature. “Many parts of the brain are organized in obvious ways: in the motor cortex, for example, stimulating a particular spot causes motion in a specific part of the body. But there is no such obvious organization in the hippocampus, so it is unclear why stimulating certain locations leads to predictable results.”