Lack of funding

Transcranial magnetic stimulation (TMS) is a neuromodulation device that is FDA-approved for use in treating depression and obsessive compulsive disorder. TMS works by applying a safe, electromagnetic field on the scalp, which can either increase or decrease neuronal communication and activity (depending on the mode of stimulation). Although it is only approved for two disorders, there has been substantial research into the potential of TMS to treat a wide range of neuropsychiatric disorders, including substance use disorders (SUDs). This project aims to develop an initial TMS protocol in a sample of healthy controls and to establish the feasibility and efficacy of using repetitive TMS (rTMS) to impact several carefully-selected cognitive, behavioral, and physiologic measures. This pilot project will enable the research team to gather baseline data using this new method and to plan longer-term programmatic studies focusing on populations with SUDs. The overarching aim of this project is to develop an rTMS protocol for use in the human laboratory setting with both healthy controls and individuals with SUDs. The investigators also hope to learn about the impact of high frequency rTMS over the DLPFC on multiple aspects of functioning including: cognitive control, impulsivity, thermal pain sensitivity, motivation, and mood.

The short-term goal of this pilot project is to establish the feasibility and efficacy of repetitive transcranial magnetic stimulation (rTMS) on cognitive, behavioral, and physiological measures in a healthy community-recruited sample to plan longer-term programmatic studies focusing on substance use disorder (SUD) populations. Primary Aims are to examine the effect of one session of left dorsolateral prefrontal cortex (DLPFC) rTMS high-frequency (10 Hz) stimulation vs. placebo stimulation (no electromagnetic field but similar auditory and tactile sensations) on: (1) cognitive control, (2), impulsivity, and (3) thermal pain sensitivity. Secondary Aims are to test effects of rTMS on behavioral motivation (monetary incentive delay task, effort choice task), mood (PANAS), peripheral biomarkers (prolactin, BDNF) and collect biosamples for future genotyping.

The investigators recognize the proposed sample size is relatively small to adequately power a full analysis across all outcomes, so will use this study to determine effect sizes for any differences to plan future studies with adequate power. Generally speaking, data will be analyzed using repeated measures ANCOVAs; covariates will include TMS resting motor threshold, sex, and age. Based on sample size calculations, the investigators intend to complete up to 30 subjects. For some outcomes, the results of previous studies indicate that a lower sample size may be appropriate, therefore the investigators will conduct interim analyses at n=18 to calculate effect sizes to determine how many more participants are needed.

Inclusion Criteria:

• Healthy
• Right handed
• 21-60 years of age
• IQ score greater than 80
• Eligible if using tobacco, alcohol, or marijuana fewer than 3 times per week; each "time" must be less than 3 cigarettes or drinks, or less than 1 marijuana "joint"

Exclusion Criteria:

• Under influence of any substances during any session
• Use of illicit substances in the past 30 days
• Pregnant
• Medical conditions that prohibit the use of rTMS (e.g. history of seizures or medications that lower seizure threshold)
• Current DSM-5 Axis I psychiatric disorders, or any history of substance use disorders.

The research team is committed to disclosing and sharing scientific findings as outlined by NIH policy guidance on Sharing Research Data and on Sharing Model Organisms (see: http://grants.nih.gov/grants/policy/data\_sharing/data\_sharing\_guidance.htm#time). We note that, "NIH recognizes that the investigators who collected the data have a legitimate interest in benefiting from their investment of time and effort. NIH continues to expect that the initial investigators may benefit from first and continuing use but not from prolonged exclusive use." The research team (PI, with advice from co-investigators) plans to share data from this project as follows. We will disseminate data using conventional means including published abstracts, conference presentations (posters and talks), news releases, and peer reviewed journal articles.

Findings from the proposed investigation will be provided to the scientific community as rapidly as possible, given the usual constraints of careful data checking, analysis, and peer review.

Qualified researchers may request in writing additional protocol materials from the PI.

Participants will be blinded to the use of active vs. sham rTMS. For the sham condition, the investigators will use a placebo figure-of-8 coil, which looks identical to the active coil, allows the same scalp placement, and produces the same auditory and tactile sensations as active stimulation without affecting cortical excitability.