The primary goal will be to identify the optimal pulse protocol by systematically measuring the efficacy of various theta burst stimulation and repetitive rTMS protocols to increase and decrease the reward positivity in dependent smokers. The secondary objective will be to measure the protocols' effectiveness to increase decision-making capacity using the probabilistic selection task (PST). The third objective will be to specifically assess whether the TMS targets has a differential impact on state levels of craving relative to baseline (Tobacco Craving Questionnaire \[TCQ\]. The investigators plan to accomplish these three objectives using a randomized, controlled experiment involving 2 sessions.
The design is primarily a randomized control-trial design (2 sessions), comparing the effects excitatory and inhibitory TMS protocols applied to a prefrontal TMS target on reward processing in smokers. Eligible smokers will be invited to attend two experimental sessions over a 1-month period, and asked to abstain from smoking 4 hrs prior to each session. For Sessions A and B, participants will be asked to provide their consent, CO levels and complete the TCQ. Compliance with the 4-hour abstinence period will be defined as breath CO less than 13 ppm. Participants will then be randomly selected to participate in Condition 1a or Condition 1b. All procedures between the two conditions will be identical except for the contrasting TMS protocols (Condition 1a: excitatory protocols, Condition 1b: inhibitory protocols) and the rewards presented in the T-maze task (Condition 1a: monetary rewards, Condition 1b: monetary rewards with cigarette cues). To streamline these studies, the left DLPFC target will be based on conventional DLPFC targeting methods (electrode position F3). For Condition 1a, the protocol administered in Session A and B will be randomized so that participants will either receive 3600 pulses of 10-Hz TMS or 3600 pulses of cTBS. For each session, participants will first engage in one block of T-maze trials (100 trials: Baseline measure). In Condition 1a, participants are told that the reward stimulus indicated 5 cents and that the presentation of the no-reward stimulus indicated the alley was empty (0 cents). Following this block of trials, participants will either receive 10-Hz TMS or cTBS over the predefined DLPFC target (F3), and then asked to complete 3 additional Blocks of the T-maze (300 trials: post-TMS). Immediately after participants complete the T-maze, subjects will be asked to complete the PST and TCQ. At the end of the Session A, participants will complete Session B on a separate day (all procedures identical as Session A). Session A and Session B will be separated by at least 2 days to minimize carryover effects. For Condition 1b, the protocol administered in Session A and B will be randomized so that participants will either receive 600 or 1200 pulses of iTBS. For each session, participants will first engage in one block of T-maze trials (100 trials: Baseline). In Condition 1b, participants are told that the reward stimulus indicated 5 cents and that the presentation of the no-reward stimulus indicated the alley was empty (0 cents). Each reward and no-reward stimulus will be paired with a cigarette cue. Following this block of trials, participants will either receive 600 or 1200 pulses of iTBS over the predefined DLPFC target (electrode F3), and then asked to complete 3 additional Blocks of the T-maze (300 trials: Post-TMS). Immediately after participants complete the T-maze, subjects will be asked to complete the PST and the TCQ. At the end of the Session A, participants will complete Session B on a separate day (all procedures identical as Session A). Session A and Session B will be separated by at least 2 days to minimize carryover effects.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
42
TMS will be delivered using a robotic neuronavigation system (Smartmove, ANT). Stimulation intensity will be standardized. Stimulation will be delivered to the L-DLPFC using a active/placebo figure-8 coil and a magventure TMS device.
Rutgers University - Newark
Newark, New Jersey, United States
RECRUITINGEvent-related Brain Potential: Reward Positivity
The reward positivity is an event-related brain potential (ERP) sensitive to reward feedback. The reward positivity will be measured during the T-maze task, where participants will receive feedback (Reward, No-reward) following choices. ERPs will be created for each electrode and participant by averaging the single-trial EEG according to feedback type (Reward, No-reward). The reward positivity will be evaluated by subtracting the Reward feedback ERPs from the corresponding No-reward feedback ERPs. The size of the reward positivity will then be determined by identifying the maximum absolute amplitude of the difference wave within a 200-to 400-msec window after feedback onset and evaluated along electrodes Fz, FCz, and Cz. The reward positivity will be measured for each pulse protocol across condition 1a and condition 1b of dependent smokers. The reward positivity will be used to measure the efficacy of the pulse protocol to modulate reward activity.
Time frame: Day 0 (day of testing)
Approach Learning
Approach learning will be measured using a Probabilistic Selection task (PST), in which subjects are shown pairs of arbitrary stimuli and must learn by trial-and-error to select one of each pair. During an initial learning phase participants are exposed to three pairs of stimuli, each of the three pairs is rewarded on 80%, 70%, and 60% of the trials. Subjects learn by feedback that some stimuli are associated with more positive feedback (Approach) and that some stimuli are associated with more negative feedback (Avoidance). To determine whether subjects learn more from positive (approach) or negative (avoidance) feedback, during a subsequent testing phase they are required to choose between novel stimulus pairs. Approach learning (accuracy and reaction time) for each proposed pulse protocol across condition 1a and 1b will be measured during the testing phase. Avoidance learning performance will be used to measure the efficacy of the pulse protocol to modulate decision making.
Time frame: Day 0 (day of testing)
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