Ultrasound-based neurostimulation in the mouse model

Ultrasound-based neurostimulation would be a useful tool prior to MR-guided focused ultrasound treatments in the brain. In this work, we report on our studies on ultrasound-based neurostimulation in the mouse model. We define the success rate as the ratio of the number of positive EMG responses to the number of sonications. A single element ultrasound transducer with a center frequency of 500 kHz was applied to the mouse head via a coupling column and coupling gel on the mouse head. EMG electrodes were placed in the mouse neck and tail muscles to measure contraction of the relevant muscles as the ultrasound transducer is moved across the mouse head. The success rate increases with ultrasound intensity or with ultrasound duration, following a sigmoidal curve. As the ultrasound frequency is increased, the ultrasound intensity must be increased for the same success rate. Movement of the ultrasound transducer across the brain changes the response in the relevant EMG systems such that the neck EMG response is stronger when the transducer is more rostrally placed, while the tail EMG response is stronger when the transducer is more caudally placed. Our findings present evidence for selective targeting in the mouse model of ultrasound-based neurostimulation.