Brain cells can be controlled by sound waves

Scientists, for the first time used sound waves to control brain cells. The technique, called sonogenetics was developed by the scientists from Salk Institute for Biological Sciences in La Jolla, California. Scientists successfully used the method on worms when they selectively activated their brain, heart, muscle and other cells by using sound waves.

This new technique has some similarities to the burgeoning field of optogenetics where light is used to control living tissue.

By using same type of low-pressure ultrasound used in medical sonograms, scientists were able to penetrate it through skin and tissue and control certain cells.

In optogenetics, a focused laser is shined on the cells which allow scientists to selectively open the channels. This method is difficult to use on cells deep in the brain since they have to surgically implant a fiber optic cable that reaches the cells. Also, light is scattered by the brain and other tissues.
The scientists decided to look for a less invasive alternative which relied on ultrasound waves for the activation of the cells.

“In contrast to light, low-frequency ultrasound can travel through the body without any scattering,” said Sreekanth Chalasani, a senior author and an assistant professor at the Molecular Neurobiology Laboratory in Salk Institute.

“This would enable us to manipulate target cells or tissues that are deep within the body without extensive surgery,”

To use ultrasound, a protein that responds to ultrasound was needed. The team identified TRP-4, a naturally occurring protein in the membranes of invertabrates. When they applied ultrasound, it triggered the gas bubbles to spread into the worm and caused TRP-4 channels to open up and activate the cells. The team was then able to genetically modify the worms by adding TRP-4 neurons and successfully activated them.

The scientists are hoping to use sonogenetics on human as an alternative way to treat Parkinson’s or other neurological diseases where a method called deep brain simulation is used by implanting electrodes in the brain to ease the symptoms of the disease.

“The real prize will be to see whether this could work in a mammalian brain,” said Chalasani. “When we make the leap into therapies for humans, I think we have a better shot with noninvasive sonogenetics approaches than with optogenetics.”

He believes that both optogenetics and sonogenetics approach shows promising results in basic research in cell activation. These methods may also be useful in therapeutics. To effectively and safely use it in humans, the scientists must develop safe ways to deliver light or ultrasound.
Other researchers involved in the study were Stuart Ibsen and Ada Tong of the Salk Institute, Carolyn Schutt and Sadik Esener of the UC, San Diego.

The study was published in the journal Nature Communications.