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.
