Feasibility and Efficacy of rTMS in Healthy Persons

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.

Eligibility Criteria:
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.