Sonogenetics is a revolutionary science that offers a noninvasive surgery using low-frequency sound to activate specific ultrasonically sensitized neurons.
A group of scientists at Salk Institute have developed a new method called sonogenetics to selectively stimulate brain, heart, muscle and other cells using ultrasonic sound waves. The technique uses the same type of waves used in a medical sonograms.
Published in the journal Nature Communications in September 2015, the new method, invented by Sreekanth Chalasani of the Salk Institute for Biological Studies is noninvasive and are able to penetrate the skin and target specific cells without harming untargeted ones. Here, the team blasted ultrasonic waves to a genetically modified nematode worm bathe in microbubbles causing it to move in a different direction.
“Ultrasound is perfect because it goes through the skin, is not scattered, and maintains energy when it penetrates the skin,” Chalasani said. “You could imagine sticking an ultrasound cap on someone’s head and using that to switch neurons on and off noninvasively.”
To conduct the experiment, Chalasani looked for a protein that was sensitive to ultrasound. He found one, called TRP-4, that occurs naturally in invertebrates.  With the genetic code for TRP-4, he used a virus to introduce it into C. elegans, a nematode. Because nematode worms are so small, he used microbubbles to amplify the sound.  The ultrasound pulses work by turning on motor neuron cells.
Researchers knew that under normal conditions worms don’t respond to ultrasound, so immersing the worms to the fluid inclosing microbubbles of gas increased the kinetic response of the activated cells. This works just like a sound amplifier which makes the sound waves stronger and switch on the activated motor neurons in the nematode. The sound waves then targeted the TRP-4 ion channels found inside the certain nematode cells. Once the TRP-4 channels opened, the corresponding cells activated and responded to the sound waves. 
While science have achieved similar method called optogenetics which uses light to switch neurons on and off, Sreekanth Chalasani, a molecular neurobiologist at the Salk Institute hoped that this new method of Sonogenetics could better improved the old technique. “Light-based techniques are great for some uses and I think we’re going to continue to see developments on that front”.
The tricky part when using light is that it scatters when it hits denser tissues, not like low- frequency ultrasound waves which can easily penetrates deep into the brain tissue and bones.
Sonogram Scans May Help Cure Neurodegenerative Disorders
As you know, ultrasound travels unhindered through the body, that being said makes it very useful for medical sonograms. Today, using high-frequency sound waves, doctors are able to scan images of different organs to identify problems or monitor developing babies in the womb. However, it turns out that ultrasound images may have another, rather surprising and revolutionary application in healthcare. They may help cure Alzheimer’s disease and treat symptoms of other neurodegenerative disorder. 
In a new study published in Science Translational Medicine, scientists found that scanning the brains of mice with a model of this disease not only helped clear the abnormal protein buildups that are associated with Alzheimer’s, but also improved their memory.  
What Holds the Future?
The study about sonogenetics is pretty impressive and many of us would like to see its application to humans at a future point, perhaps an alternative to the highly invasive procedure called deep-brain stimulation which is presently used to cure Parkinson Disease and other degenerative disease by sending electrical impulses to specific regions of the brain.
Sonogenetics indeed opens up new possibilities for how we control cell’s behavior through acoustic pulses and this would likely lead to more people going into the field and properly investigating how sound can heal.