A new method that shows how individual neurons in a nematode may be stimulated by ultrasound through the use of genetic modification and microbubbles, is reported online in Nature Communications. The authors hope that this method will allow neuron stimulation in deep tissues in a less invasive way than existing light-based methods such as optogenetics.
Current methods to activate or deactivate neurons, such as optogenetics, require invasive surgical procedures that make their use difficult in deeper brain regions. Ultrasound is well suited for stimulating populations of neurons as it can reach deep tissue and go through the bone, as shown by previous research both in excised neurons and in live animals. However, the stimulation of individual neurons has been difficult as the focal zone of ultrasound is larger than individual cells.
Sreekanth Chalasani and colleagues describe a non-invasive method to manipulate individual neurons using genetic modification in conjunction with gas-filled microbubbles that amplify ultrasound, which they name 'sonogenetics'. The authors investigate the method in the nematode Caenorhabditis elegans and find that while non-modified, wild-type C. elegans are insensitive to low pressure ultrasound, genetic modification sensitises neurons and can then result in alternations in the nematode’s motor behaviour. The authors suggest that this method could also be used to manipulate cellular functions in other animals.