UC San Diego

Neural stimulation with focused ultrasound is a rapidly developing research field. This thesis demonstrates design and validation of a comprehensive focused ultrasound neural stimulation (FUS-NS) research system that can both generate ultrasound pulses with user-definable parameters and process the elicited Electroencephalographic (EEG) responses from human test subjects. Several ultrasound transducers were characterized with different methods including both simulation and experimental measurements to ensure safety and confirm parameter space. Parameter sets were swept in acoustic tank and measured with hydrophone before human subject tests to ensure safety. EEG data were analyzed with custom-built MATLAB script to sort and extract user-definable patterns. Different versions of the transmit sub-system (TX) was built and tested and will be presented in this thesis. Our human study showed that FUS-NS system was safe for use in human subjects and activated peripheral neural nociceptors (free nerve endings), and a resultant painful sensation was perceived when the system was tested. The pain sensation was recorded with our NR EEG evoked potentials (EP). The human subject study (N=3) carried out confirmed safety of the system as well as all the proposed functionalities. This system will greatly facilitate the research in focused ultrasound neural stimulation. Our laboratory has now moved to characterize additional FUS-NS aimed to stimulate axonal neuronal structures.