Parkinson’s disease (PD) affects about 1 million people in the United States. It’s a progressive disease, often beginning in middle age, but it can take over the body in a matter of just a few years, leaving patients unable to care for themselves. There is currently no cure and while there have been promising research studies, the exact cause is still not known. One form of treatment sounds harsh and almost barbaric, but has shown some success in patients. It’s Deep Brain Stimulation (DBS). A system is implanted in the brain and connected to a transmitter also implanted, usually in the chest area, and electrical impulses are delivered directly to the area of the brain where PD tremors originate. The surgery to implant the electrodes, wires and transmitter is tricky however and not every patient is a candidate for surgery. Scientists at the Massachusetts Institute of Technology (MIT) in collaboration with Beth Israel Deaconess Medical Center (BIDMC) and the IT’IS Foundation in Zurich have developed a form of DBS that is non-invasive and does not require complicated surgery.
Using electrodes placed on the scalp, their system could allow patients with PD or other forms of tremor or brain illness, to get relief without having to undergo a risky surgery of opening the skull to place electrodes deep into brain tissue. Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT, and the senior author of the study explained, “Traditional deep brain stimulation requires opening the skull and implanting an electrode, which can have complications. Secondly, only a small number of people can do this kind of neurosurgery.”
DBS is a technique that has been investigated for a variety of brain disorders including obsessive compulsive disorder, depression and epilepsy and if this newer non-surgical system can work, it would make the technology far more accessible to more patients. In tradition DBS, electrodes are surgically implanted deep in the subthalamic nucleus of the brain. It’s not an easy part of the brain to access and of course the surgery is extremely difficult. The MIT team wanted to see if there was a way to electrically stimulate this area from outside the skull. They used the concept of “temporal interference” to achieve this.
First, they generated two high-frequency electrical currents, from hardware placed on the scalp. Aiming the currents at the same region of the brain individually wouldn’t be enough to influence any neurons to fire, but the two currents interfere with each other and at the point of intersection a low-frequency current is picked up by neurons in the subthalamic region. The currents are harmless to the tissue they pass through, but when they are joined, the low-frequency result is enough to manipulate the activity of the neurons.
The system is quite customizable, just by changing the number and location of the electrodes on the scalp to fine tune the frequency and aiming or altering the currents to target specific neurons and networks in the brain. Boyden explained that the technology could have multiple uses, “You can go for deep targets and spare the overlying neurons, although the spatial resolution is not yet as good as that of deep brain stimulation. The fact that only two sources are needed and one can conceptually steer the focus is fascinating. I can see a possible future where this technology could be made portable for non-invasive deep brain stimulation as a therapy.” The system was tested on mice at MIT’s Picower Institute for Learning and Memory and researchers there found that it was possible to stimulate small regions deep within the brain, including the hippocampus. Changing up the currents and the placement of the electrodes also resulted in triggering the animals to move their ears and whiskers. Take a look at the video below to learn more about this exciting research.