Neuroscientists are always looking for ways to influence neurons in living brains so that we can analyze the outcome and understand both how that brain works and how to better treat brain disorders. For the last two decades the go-to tool for researchers in my field has been optogenetics, a technique in which engineered brain cells in animals are controlled with light. This process involves inserting an optic fiber deep within the animal’s brain to deliver light to the target region. Ultrasound is a great way to control cells. Since sound is a form of mechanical energy, if brain cells could be made mechanically sensitive, then they can be modified with ultrasound.
This research allowed the discovery of the first naturally occurring protein mechanical detector that made brain cells sensitive to ultrasound. The technology works in two stages. First new genetic material is introduced into malfunctioning brain cells using a virus as a delivery device. This provides the instructions for these cells to make the ultrasound-responsive proteins. The next step is emitting ultrasound pulses from a device outside the animal’s body targeting the cells with the sound-sensitive proteins. The ultrasound pulse remotely activates the cells. Researchers discovered that neurons with the TRP-4 protein are sensitive to ultrasonic frequencies.