Dose-Dependent Effects of Low-Intensity Focused Ultrasound

Inclusion Criteria:

* Age 18 to 65 years.
* Body mass index 17-38 kg/m2.
* Fluent English speaker, capable of providing written informed consent.
* Overall Anxiety Severity and Impairment Scale \<8 and Patient Health Questionnaire-9 \<10
* A person of childbearing potential must have a negative urine pregnancy test at screening
* Consent that random observations of pathology are possible (e.g., brain abnormality seen during imaging).

Exclusion Criteria:

* Inability to provide informed consent including medical, psychiatric, or other conditions that restrict the patient's following abilities: to interpret the study information, to give informed consent, to adhere to the rules of the protocol, or complete the study.
* No telephone or easy access to telephone
* Has active suicidal ideation (as measured by Suicide-Risk-Assessment-C-SSRS "Yes" answers to items 3, 4, or 5 Suicidal Ideation-Past 1 month section, or any "Yes" answer to any of the items of Suicidal Behavior-Past 3 months section), or any suicide attempt in the last 3 months
* Has positive test result(s) for alcohol of abuse (including methadone, opiates, cocaine, amphetamine/methamphetamine and ecstasy), or substance use disorder including alcohol, stimulants, sedatives, and cannabis exceeding mild severity in the last 6 months
* Has a lifetime APA Diagnostic and Statistical Manual of Mental Disorders (DSM)-5th edition including major depression, generalized anxiety disorder, specific phobias, panic disorder, post-traumatic stress disorder, schizophrenia spectrum and other psychotic disorders, obsessive-compulsive disorder, or bipolar disorder.
* Benzodiazepines or anticonvulsants in the 7 days prior to participation.
* MRI contradictions as detected by the MRI Safety Screen including claustrophobia and unwillingness and inability to complete scans (e.g., unable to lie on one's back for 60 mins.
* Clinical history of relevant structural pathology of the central nervous system, including Parkinson's disease, multiple sclerosis, and brain malignant neoplasia.
* History of unstable liver or renal insufficiency; significant and unstable cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurological, hematological, rheumatological, or metabolic disturbance; or any other condition that, in the opinion of the investigator, would make participation not be in the best interest (e.g., compromise the well-being) of the subject or that could prevent, limit or confound the protocol-specified assessments, including uncontrolled diabetes mellitus (ss evidenced by fasting glycemia ≥ 120 mg/dL or hemoglobin A1c ≥ 6.5%) or hypertension (as evidenced by two consecutive readings ≥ 140/90 mmHg) to ensure medical stability throughout this longitudinal study.
* Moderate-to-severe traumatic brain injury or any other clinical neurocognitive disorder.
* Clinical history of at least minor neurocognitive disorder of any origin.
* Prescription of a medication outside of the accepted range, as determined by best clinical practices and current research.
* Use of any psychotropic medication.
* Unwillingness or inability to complete any major aspects of the study protocol.
* Prior neurosurgery.
* Non-correctable vision or hearing.