The goal of this study is to investigate the effects of a non-invasive, low intensity focused ultrasound (LIFU) stimulation on seizure frequency and the epileptogenic network in drug-resistant epilepsy. LIFU uses focused sound waves to modulate deep brain regions and to enable changes in brain network activity. Encephalography (EEG) and behavioral tasks will also be used to study how LIFU affects brain activity.

Inclusion Criteria

• Male or female between 21 and 65 years of age at screening
• Clinical diagnosis of drug-resistant epilepsy with on average, 4 or more seizures per month.
• Able to provide informed consent (or assent when applicable) by the subject or subject's legal representative.
• Be willing to undergo a brain MRI.
• Be able and willing to wear a headband during the treatment duration.
• Be able to complete scheduled visits and daily seizure logs.

Exclusion Criteria

• Has a craniotomy or pathologic intracranial lesion (e.g. vascular malformations) in the trajectory of the focused ultrasound beam.
• Pregnant, breastfeeding, is attempting pregnancy, or unwilling to practice birth control during participation in the study.
• Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data.
• Has any unstable medical or psychiatric disease.
• Any contraindications for completing a brain MRI scan.
• Has evidence of any other clinically relevant neurological disorder at the time of screening, including Alzheimer's disease, frontotemporal dementia, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis.

Individual participant data (IPD) will not be shared with outside researchers at this time to ensure the protection of participant privacy and to maintain strict compliance with the University of California San Francisco IRB approved protocol.