Low Intensity Focused Ultrasound for Tobacco Use Disorder: High Resolution Targeting of the Human Insula

Tobacco use disorder (TUD) remains the leading cause of preventable death in the world. Costs of smoking related illness in the United States totals more than $300 billion each year. The majority of adult cigarette smokers want to quit and more than half make an attempt but fewer than 1 in 10 smokers successfully quit at the end of 1 year. Rates of cigarette smoking are higher and cessation rates are lower in the veteran population in the United States compared to the nonveteran population. Noninvasive neuromodulation holds promise as a therapeutic approach to TUD as evidenced by the recent food and drug administration (FDA) clearance of deep transcranial magnetic stimulation (TMS) as such a treatment. One additional, emerging potential therapeutic is using low-intensity focused ultrasound (LIFU) to inhibit cortical and deep brain regions. The enormous potential of LIFU stems from the ability to focus ultrasound through the intact skull to a millimeter-sized focal spot size anywhere in the brain. This makes it a powerful alternative to both invasive neurosurgical procedures and other noninvasive brain stimulation techniques such as TMS that have limited spatial resolution and can only reach superficial areas of the brain. One promising target to treat TUD is the dorsal anterior insular cortex (dAI), a brain structure whose function is linked to the desire to smoke. The dAI is a part of the salience network (SN) that is involved in assigning significance and emotional value to stimuli and is consistently activated with exposure to smoking cues and craving. Remarkably, humans with damage to the insula were able to stop smoking easily and without experiencing cravings or relapse. As such, the insula is a promising target for reducing craving and use in individuals with TUD. Unfortunately, the dAI is small and lies deep within the lateral sulcus covered by the overlying opercula of the temporal lobe and is not accessible with conventional noninvasive neuromodulatory techniques. LIFU can selectively target the dAI and provides a potentially transformative method to reduce nicotine craving and addiction. The overall purpose of this proposal is to inhibit the dAI with LIFU to determine the causal role for the dAI in smoking cue induced craving which is a clinically important behavior which has been associated with the severity of nicotine addiction.