Studying the effects of Low Intensity Focused Ultrasound (LIFU) to the dorsal posterior insula (dPI) and dorsal anterior cingulate cortex (dACC) on autonomic control using a test to probe the autonomic system. A cold pressor task will be performed pre and post LIFU application. Physiologic recordings will be recorded throughout.

Characterize the effect of LIFU to the bilateral dorsal posterior insula (dPI) and dorsal anterior cingulate cortex (dACC)) on autonomic control. The dPI is a critical brain area involved in autonomic function, being a core recipient of ascending pain and autonomic function. Similarly, the dACC has been strongly implicated in autonomic control and works with the insula for autonomic processing. Inconveniently, these brain regions lie deep to the cortex, prohibiting access using conventional noninvasive methods like transcranial magnetic stimulation (TMS). LIFU can be focused at depth to reach the insula and ACC with high spatial precision. However, the effect of LIFU to the human dPI and dACC on autonomic control is unknown. To address this, the investigators will target the right dPI and the dACC to assess how LIFU to each of these areas affects autonomic responses and subjective report to the cold pressor task, a safe, reproducible autonomic challenge.

Inclusion Criteria:

• Does not meet exclusion criteria.

Exclusion Criteria:

The exclusion criteria below are regularly implemented in MRI, CT, and EEG experiments for the safety of the subjects and for data quality assurance.

• Claustrophobia (scanning environment may be uncomfortable).
• Contraindications to MRI: including pacemaker, aneurysm clips, neurostimulators, cochlear implants, metal in eyes, steel worker, or other implants.
• Contraindications to CT: pregnancy
• Active medical disorder or treatment with potential central nervous system (CNS) effects (e.g. Alzheimer's) -
• History of neurologic disorder. (e.g. Parkinson's, Epilepsy, or Essential Tremor)
• History of head injury resulting in loss of consciousness for >10 minutes.
• History of alcohol or drug dependence (through self-report).
• History of cardiac disease
• A current or prior use of any cardiac medication (e.g. beta blockers or other anti-arrhythmics)
• A history of diabetes mellitus or use of diabetic medications (e.g. metformin).

Sham application during a single randomized session (1 of 3 sessions).