For many years, people have turned to electric shock therapy for a variety of ailments—most notably for the treatment of mental illnesses. Now, a study shows that targeted electric shocks to the brain—through an implant—could eventually bring relief to those suffering from Alzheimer’s and dementia by improving their memories. Based on this technology, researchers are also developing a prosthesis that would enhance your brain’s natural abilities.
Memory Boosting Implants
Researchers from the University of Southern California (USC) implanted what they call a “memory prosthesis” in 20 volunteers—the first human trial of its kind. These participants had previously had electrodes implanted in their brains for epileptic treatment, so the memory system did not necessitate an additional surgery. Through the electrodes, the implant delivers small electric shocks to part of the brain most involved in memory and learning—the hippocampus. The shocks are devised to mimic the pattern of healthy brain activity and the way humans process memories.
When stimuli enter the brain, a memory generates from complex electrical signals traveling through various areas of the hippocampus. Along the way, the signal is re-encoded until the final stage, at which point it gets diverted for long-term storage. Any brain damage that prevents this coding or translation process could prevent a long-term memory from forming. For instance, people with Alzheimer’s can often remember events from the distant past—before the disease damaged their hippocampus—but not more recent events.
In the USC study, the researchers successfully boosted the memory capacity of humans by supplying the proper electrical signals to the participants’ hippocampus to boost the regular neural pathways used to create a memory.
The research team first gathered data about the participants’ brain activity with the implant in place. During this phase, each participant performed a preliminary short-term memory test, attempting to recall unusual shapes five to 10 seconds after seeing them. Then, the participants engaged in a more challenging version—known as a working memory test—where they were asked to recall images seen 10 and 40 minutes ago. The team followed participants’ brain activity during these tests and designed an electrical stimulation to target the areas that lit up during their best recall.
During the second round of testing, the team broke the stimulation patterns into thirds: one-third of the time simulating their observations from the pre-test—which would theoretically be helpful; another third supplying random stimulation; and another third providing no stimulation. The simulated or “correct” patterns improved short-term memory by 15 percent and working-memory 25 percent more than no stimulation. The random stimulation decreased performance.
According to associate professor of biomedical engineering research Dong Song, who presented the study’s results at the Society of Neuroscience meeting in Washington DC over Veteran’s Day weekend 2017, this represents the first time such a device has been shown to improve human cognition.
“We are writing the neural code to enhance memory function,” Song said. “This has never been done before.”
The achievement is based collaborative work between researchers at USC and Wake Forest Baptist Medical Center to create the brain implant and necessary models and algorithms. It was previously successfully tested on animals prior to human study.
Ted Berger, of USC’s Viterbi School of Engineering, has been researching the foundation for the device for decades and helped Song find a way to simulate the process of translating short-term memories to long-term ones—despite the fact that its content is unreadable from its electrical signal. Even more challenging, the implant must bypass any damaged areas of the hippocampus and deliver the signal to the next region with the new proper translation.
Berger explains, “It’s like being able to translate from Spanish to French without being able to understand either language.”
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