Researchers at the University of Washington in St. Louis have developed a technique they call sonothermogenetics, which combines genetic and ultrasound modification to achieve non-invasive neuronal control in deep brain regions. The technique involves using viral vectors to introduce encoding of genetic material for ion channels into specific neurons in the brain. An external ultrasound probe can provide gentle heating that activates ion channels, allowing researchers to turn specific neurons on or off. The new approach may end up leading to effective non-invasive treatments for neurological conditions such as Parkinson’s disease.
Techniques that allow researchers to turn neurons on or off have increased in popularity in recent years, both as a research tool and as a potential mechanism for treating neurological disorders, such as epilepsy or Parkinson’s. One of the most widely reported is optogenetics, in which genetically modified neurons are turned on or off by light. However, this approach usually requires the surgical implantation of optical fibers in the brain.
The latter technique can provide deep brain stimulation, but without the need for surgical procedures. It is based on the delivery of viral vectors to the brain that can be targeted to specific neurons. Vectors carry genetic material that encodes heat-sensitive ion channels. Once a neuron expresses these channels, it can be guided by an externally applied ultrasound, which can create heat in a small area of the brain (~ 1 mm).
To date, the research team tested the technique in mice and delivered the TRPV1 ion channel to specific neurons, while using a head-mounted ultrasound unit to achieve localized heating. “We can move the ultrasound device that is carried in the head of moving mice to go to different locations around the brain,” Yaoheng Yang, a researcher involved in the development of the new technology, said in a press release . “Because it is non-invasive, this technique has the potential to be scaled up to large, potentially human animals in the future.”
The technique successfully affected the behavior of the treated mice. “Our work provided evidence that sonothermogenetics evokes behavioral responses in freely moving mice as they target a deep site in the brain,” said Hong Chen, another researcher involved in the study. “Sonothermogenetics has the potential to transform our approaches to neuroscience research and discover new methods for understanding and treating human brain disorders.”
Watch a video on the technique below:
Study the magazine Brain stimulation: Sonothermogenetics for non-invasive and cell-specific deep brain neuromodulation