Deep brain stimulation, or using mild electrical shocks to targeted parts of the brain with the purpose of affecting how they function, provides a whole new approach to dealing with neurological conditions that have challenged doctors for a long time.
For years now, it’s been used to treat Parkinson’s disease. By sending small shocks to regions of the brain that control movement, this stimulation can help keep the tremors of Parkinson’s under control.
It works like a kind of pacemaker for the brain. A surgeon inserts a probe into a specific area of the brain, and it’s connected by wires under the skin to a battery pack implanted near the top of a person’s chest. A doctor sets the strength of the electrical pulse, how long it lasts and how often it occurs. One type of stimulation can boost brain cell activity, another can slow it down.
Not surprisingly, as the technology and treatment have become more refined, scientists have started to look at other ways brain stimulation might be used, and not just to treat neurological damage from Alzheimer’s or traumatic brain injuries, but also to address mental health disorders and even, to some degree, behavior. There are studies underway, for instance, to see if it can help people stop smoking.
Here’s a sampling of the latest brain stimulation research:
Slowing down Alzheimer’s: Alzheimer’s disease remains one of medicine’s most daunting challenges, both in terms of pinpointing a cause and developing a truly effective treatment. Now a team led by scientists at Johns Hopkins University is conducting a clinical trial to see if deep brain stimulation can slow memory loss and cognitive decline.
The research involves placing implants into the brains of about 40 patients with mild Alzheimer’s disease and measuring progression of the disease over an 18-month period. Specifically, the devices are being implanted in the patients’ fornix—a bundle of nerve fibers connecting the left and right sides of the hippocampus. That’s the region of brain associated with memory. The theory is that brain stimulation in this area could slow the rate of damage to the fornix and even create new brain cells in the hippocampus.
The most recent phase of the trial, expected to last four years, focused on the safety of the implants in Alzheimer’s patients. So far, it has found no serious adverse effects.
So long to the big queasy?: Researchers at Imperial College London say that brain stimulation could even be used to ease motion sickness. Scientists aren’t absolutely certain what causes the queasy sensation, but they believe it has to do with the brain trying to process conflicting signals from our ears and our eyes when we’re in motion. Previous research has determined that a well-functioning vestibular system—that’s the part of the inner ear that senses movement—makes it more likely that someone will feel that nauseating sensation.
So, the researchers wondered what would happen if they used an electric current to mute the signals from the vestibular system to the brain. They worked with 10 men and 10 women volunteers who agreed to wear a cap fitted with electrodes and then, for 10 minutes, receive a mild electrical current designed to inhibit brain cell activity. That was followed by a ride on a chair that rotated and tilted at different speeds to make them feel sick.
It turned out that those who received stimulation that reduced brain cell activity were less likely to feel nauseous and recovered more quickly than people whose brains were stimulated to boost cell activity. Now, the researchers are talking with potential partners about developing a portable anti-nausea stimulation device you could pick up at the drug store.
Memories are made of this: At a conference earlier this month, DARPA, the research arm of the Defense Department, announced that as part of a study it has funded, patients who were given brain implants scored better on memory tests. Traumatic brain injuries are a big issue for the U.S. military—almost 300,000 members of the service have been treated for one since 2000. So DARPA is leading research efforts into how electrical stimulation might be used to help people with damaged brains create and retrieve memories.
Scientists having been working with brain surgery patients who have volunteered to be part of the memory project. The goal is to more clearly identify the process for how the brain forms and recalls memories and then use mild shocks from implants to recreate that process. It’s only a year into the project, but DARPA says that based on the results so far, it appears possible to map and interpret the neural signals coming from a brain as it encodes or retrieves a memory, and then actually improve that recall by electrically stimulating targeted sections of the brain.
Put down that cigarette: Another project in the early stages is looking at how brain stimulation might help people fight cravings for cigarettes or unhealthy food. Caryn Lerman, senior deputy director of the University of Pennsylvania’s Abramson Cancer Center, recently received a grant to investigate whether applying electrical shocks to sections of the prefrontal cortex behind the forehead—a brain region tied to self-control—can help people resist urges to engage in unhealthy behavior.
The idea is that if targeted correctly, this stimulation could strengthen pathways being used to fight the desire to light up. Preliminary results of an experiment involving 25 smokers found that after a 20-minute session with electrical stimulators strapped to their foreheads, people were able to wait longer before they reached for a cigarette than those who received a placebo treatment. They also smoked fewer cigarettes.
Stroke recovery: Scientists at the Cleveland Clinic have applied to the Food and Drug Administration (FDA) for permission to begin testing deep brain stimulation on human stroke victims. The treatment seemed to have worked with rats—it appeared to promote the growth of new neurons in the brain.
Not that anyone thinks that this can provide a cure for strokes. When they occur, the blood supply to the brain is cut off and some areas just shut down, while communication to other regions is disrupted. Electrical stimulation can’t bring dead neurons back to life. But it could help create new neural connections, particularly in the cerebellum, the part of the brain that controls voluntary movements. The hope is that parts of the brain that are still healthy would then be better able to compensate for damaged ones.
About 800,000 people in the U.S. suffer strokes every year. And, according to the National Stroke Association, about half of those who survive become severely debilitated.
Boosting empathy: But what about using brain stimulation to change how people feel? Researchers at Harvard University and Vanderbilt University have ventured into that territory with an experiment related to the doling out of justice.
They presented 66 volunteers with stories about a fictitious person named John—specifically they related a range of crimes he had committed and his mental condition when he had committed them. Beforehand, some of the participants were given a form of brain stimulation that could disrupt activity in the prefrontal cortex, which plays a key role not just in self-control, but also decision-making. For others, the stimulation device was attached, but never turned on.
The volunteers were asked to decide how blameworthy John was and also to determine, on a scale of 0 to 9, how extreme his punishment should be. What the researchers found is that the people whose brain activity was disrupted chose less severe punishments.
Which raises perhaps the biggest question about brain stimulation: When does fixing the brain turn into changing the brain?