Transcranial Magnetic Stimulation in Smokers: an Examination of Mediating Neural Pathways.

The study will include functional magnetic resonance imaging at baseline as well as demographic, psychological, and tobacco use assessments. Following initial assessment, participants will undergo one active rTMS session (20 Hz rTMS, 900 pulses per session, applied to left DLPFC). The outcome session will include assessments repeated from baseline.

The current proposal will examine the following aims. Aim 1: To test the potential for active rTMS to improve cognitive control of craving. Hypothesis: Active rTMS (compared to sham rTMS) will result in significant improvement in control over craving assessed by self-reported craving during the ROC task as well as in terms of activity in prefrontal regions associated with cognitive control during the ROC task.

Aim 2 (feasibility): To examine the feasibility of using fMRI BOLD activation in the DLPFC during the ROC task to target rTMS. BOLD activations during successful control over craving trials will be examined in terms of their reliability within participant and their feasibility as a target for rTMS delivered via standard figure 8 coil (capable of inducing synaptic firing 1.5-3.0 cm beneath the scalp). Additionally, the coordinates for the target identified via BOLD activation during the ROC task will be compared to the coordinates for the target identified by using standard neuronavigation to the DLPFC via anatomical fMRI, in order to determine if these areas are distinct in terms of the direct effect of the stimulation field (approximately 5 cm2).

Inclusion criteria

• Smokers endorsing atleast moderate dependence (total Fagerstrom for Cigarette Dependence score > 4)
• Endorsing no specific plan to quit smoking in the next 3 months.
• Must meet safety guidelines for application of rTMS
• 18-60 years of age
• Smoked cigarettes regularly for at least one year
• Currently smoke at least 10 cigarettes per day
• Have a carbon monoxide (CO) level greater or equal to 10 ppm
• Currently be using no other nicotine products.

Exclusion criteria

• Subjects will be excluded if they meet criteria for current alcohol (moderate - severe), current substance dependence, current affective disorder (depression, dysthymia, or mania) or current psychotic symptoms as assessed by the (MINI) International Neuropsychiatric Exam
• Are currently pregnant or lactating, or intend to become pregnant
• Have a health condition for which rTMS is contraindicated
• Submit a urine drug screen positive for illicit substances or substance misuse.