Electricity on the Brain: Can Transcranial Magnetic Stimulation Boost Memory?

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Electric stimulation might help the brain's regions work together better, improving memory. Denis Balibouse/Reuters

For many centuries, people have used electricity to heal the brain. “Electric eels and fish,” PBS points out, “were used by people in ancient times to treat headaches and mental illness.” While sticking sea creatures on our skulls fell out of practice, since the advent of electroconvulsive therapy (ECT) in 1938, doctors have been using electric current to generate small seizures in the brain in order to treat patients whose severe depression, mania, catatonia and dementia-caused aggression have been resistant to medications and therapy, according to the Mayo Clinic. Electroconvulsive therapy is still commonly used today, with some heralding it as the "most effective treatment known for severe depression," but its continued popularity belies a very dark side: Throughout its history, ECT has been used abusively—often without the anesthesia or muscle relaxants provided alongside stimulation to make patients "unconscious and unaware of the procedure" and "minimize the seizure and prevent injury," per the Mayo Clinic. 

Researchers at Northwestern Medicine have now discovered another therapeutic use for applying electric current to the brain: bolstering memory. According to a study in the August 29 issue of Science, transcranial magnetic stimulation (TMS)—put simply, using a powerful electromagnet to shoot electricity into a person’s head—can stimulate the parts of the brain associated with memory, such that the neurons in that brain region work better together.

The researchers learned of TMS’s positive impact on memory by first figuring out which regions of the brain worked with the main memory structure, the hippocampus, and then testing the treatment's influence on these areas. They administered MRIs to 16 healthy individuals, mapping the brain’s memory network and establishing a baseline of proper cognitive function in this "memory network,” explains study senior author Joel Voss, assistant professor of medical social sciences at Northwestern University Feinberg School of Medicine. Then, the researchers brought this same group into the lab and administered 20 minutes of TMS, on five consecutive days, while monitoring them with MRI as well as giving them memory tests. (As for how TMS is administered: Voss describes the TMS device as an 8-inch plastic oval, with a tube sticking out, which technicians put against the back of a subject's head. The subjects sit in a chair for about 20 minutes, during which testers administer two seconds of TMS for two seconds every 30 seconds. While it sounds "kind of like a machine gun firing," Voss says it's not painful and merely feels like a light tapping.)

So what happened?

“At baseline, these regions work together fairly well,” Voss says. “Over the course of five days of TMS treatment, they work together better. They’re working even more in concert with one another—like an orchestra getting a better conductor.”

While Voss and his team tested healthy individuals, the research has dramatic implications for memory-impaired individuals, such as Alzheimer’s patients and stroke victims, as well as those who have suffered from memory loss due to psychiatric conditions like schizophrenia. To date, drugs and surgery don’t work to boost memory, Voss says, meaning that “currently there are no effective treatments for any of these conditions.” The team will soon conduct the same TMS experiment on older adults, suffering from age-related memory decline, as well as individuals in the earliest stages of Alzheimer’s disease, Voss says.

Voss also makes clear that this treatment is not intended for healthy individuals seeking to become superhuman, saying: “We are not going to bring in a healthy, walking, talking, person and turn them into a memory champion by administering this.”

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