Beamforming Design For High-Resolution Low-Intensity Focused Ultrasound Neuromodulation

Low-intensity focused ultrasound (LIFU) has been shown to modulate neural activity. Recent experiments suggest potential applications of LIFU stimulation for treating neuropsychiatric disorders like depression and Alzheimer's. The modulation effect is usually positively correlated with the ultrasound intensity, and there exists a minimum intensity threshold for the neuromodulation to be effective. Therefore, precise configuring of the ultrasound transducer is required to sonicate the target brain region at the desired intensity with appropriate spatial resolution. In this study, we investigate the optimization of targeting through fine temporal and spatial power delivery control of a phased array of ultrasound elements. A novel metric of the ultrasound neuromodulation resolution is proposed, and an optimization problem is formulated and solved to minimize side effects in the form of off-target region sonications. Simulation results show that our method is able to significantly improve the focusing resolution compared to the benchmark and reduce the volume experiencing possible off-target neuromodulation.