Deep brain stimulation is paying off on neurological disorders like Parkinson's and epilepsy, but it requires surgical implants. Idem optogenetics, for which it is necessary to implant optical fibers on the brain.
A multidisciplinary team from Washington University in St. Louis has developed a new brain stimulation technique. It's called Sonothermogenetics, and it uses focused ultrasound that can activate and deactivate specific types of neurons in the brain. It is able to precisely control motor activity without the implantation of surgical devices.
Why is it called sonothermogenetics?
The team, led by Hong Chen, assistant professor of biomedical engineering and radiation oncology, is the first to provide direct evidence that this technology works. A combination of the ultrasound-induced warming effect and genetics. It is also the first work to show that sonothermogenetics can robustly control behavior by stimulating a specific target deep in the brain.
The results of the three years of research, funded in part by the National Institutes of Health's BRAIN Initiative, were published online on Brain Stimulation May the 10 2021.
Research on Sonothermogenetics
The senior research group included renowned experts in their fields, from different universities. A technique such as that of Sonothermogenetics could only be developed starting from different knowledge: biomedical engineering, radiology, physics, medicine, anesthesiology and pharmacology.
"Our work has provided evidence that sonothermogenetics evokes behavioral responses in mice," says Chen. "Sonothermogenetics has the potential to transform our research approaches, and discover new methods for understanding and treating human brain disorders."
How it works
Using a mouse model, Chen and the team delivered a viral construct containing TRPV1 ion channels to genetically selected neurons. Then, via a wearable device, they delivered a small heat boost via low-intensity focused ultrasound to selected neurons in the brain. The heat, only a few degrees warmer than body temperature, activated the TRPV1 ion channel, which acted as a switch to turn neurons on or off.
"We can move the ultrasound device worn on the head of the freely moving mice to reach different positions in the whole brain," he says. Yaoheng Yang, first author of the article.
Being non-invasive, this technique has the potential to be scaled up to large animals and in the future to humans.
Sonothermogenetics promises to target any location in the brain with pinpoint accuracy, without causing any harm.