A neat new proof of principle study carried out with a very well-studied worm (Caenorhabditis elegans) shows that it is possible to affect neurons using ultrasound. The worms, which admittedly have only 302 neurons, could be made to change their direction of crawl using low-frequency ultrasound. Links to a BBC article about the work, as well as to the published article itself, have been posted in Neuro-Psych:
Sound waves used to activate brain cells in a worm
Sonogenetics is a non-invasive approach to activating neurons in Caenorhabditis elegans
