South Korea’s Gwangju Institute of Science and Technology (GIST) has completed a preclinical study for a noninvasive therapy for Alzheimer’s disease. The "ultrasound-based gamma entrainment” technique involves syncing up gamma waves, or brain waves above 30 Hz, with an external oscillation of a given frequency. This happens naturally by exposing a subject to a repetitive stimulus, such as sound, light, or mechanical vibrations.