RecruitingDevice studyUltrasound Neuromodulation in Essential TremorThis study is being done to test whether low-intensity focused ultrasound (LIFU) (low energy sound waves) cause temporary changes in brain activity and behavior when directed at particular parts of the brain. By targeting LIFU to the parts of the brain thought to be responsible for essential tremor (ET), and measuring any associated improvement in tremor, the investigators hope to show that LIFU can be a useful tool for studying the brain circuits responsible for tremor and other brain disorders.