New Noninvasive Way to Stimulate Deeper Brain Areas

For years, neuroscientists have been looking for a way to stimulate deeper brain regions that does not involve surgery. When it comes to stimulating brain areas there are really only two options: invasive surgery to stimulate deeper brain regions or noninvasive surface level stimulation. There are major pros and cons to both of these methods. Deeper brain stimulations such as ECOG, or electrocorticography, requires surgery where they remove part of the patient’s skull and place electrodes on the brain. This provides better localization and allows them to target deeper brain areas, but it is obviously extremely invasive and is only performed on people who already need brain surgery for medical reasons. Surface level stimulation such as EEG, or electroencephalography, involves the patient wearing a skull cap with electrodes on it. The benefits are it is noninvasive and can be used on a wider range of people. However, researchers are restricted to only stimulating surface level structures in the brain and it also has poor localization.

Now, researchers might have just discovered a method that is the best of both worlds, called temporal interference. The method involves beaming multiple electric frequencies that are too high for neurons to respond to from electrodes on the skull’s surface. Where the frequencies intersect in the brain end up canceling each other out and whatever the difference is between the frequencies stimulates that area of the brain. So for example, if you deliver 1,000 hertz and 1,001 hertz to an area in the brain, they will cancel each other out and that area will react as if you were stimulating it with 1 hertz. However, all of the other areas that the 1,000 hertz is going through will not react because the frequency is so high that it moves faster than our brains can process. It is a similar concept to why we cannot hear sonar. This method provides researchers with precise localization, which they further tested by aiming electricity at certain areas in mice’s motor cortices. This resulted in the mice moving their fore-paws, whiskers, or ears.

With this new method, comes a lot of practical questions. The major one being that this study was done with rats, so how will it work on humans? In an attempt to begin to answer this question, the study’s senior author and co-director is testing the method on people without disorders to see if it works in the human brain. There are other questions such as, how it would be used on patients with complex diseases, like Parkinson’s, who would need continuous stimulation. Also, would patients wear a portable electricity-delivery device? Another concern is making sure to avoid brain areas that would cause motor contractions or speech and vision impairments. One hope that researchers have, is that temporal interference can be developed for patients with epilepsy and provide them with an alternative to the extremely invasive procedure of ECOG. This method is something that neuroscientists have been wanting for a long time and if it is proved to be effective and safe through more research, temporal interference could be used to help people with a range of neurological and psychiatric disorders.

https://www.nytimes.com/2017/06/01/health/new-electrical-brain-stimulation-technique-shows-promise-in-mice.html?rref=collection%2Fsectioncollection%2Fhealth