the participant will receive a type of TMS called repetitive TMS (rTMS) wherein the magnetic pulses delivered will be close together in a rapid sequence over the dlPFC. Participants receive excitatory rTMS with a stimulation frequency of 20 Hz between 100-120% of their resting motor threshold.

Sham rTMS will be the same as real rTMS, except a special sham coil will be used, which produces the same sensation on the scalp of the patients as the real coil but delivers no magnetic stimulation to the brain.

The participants undergo Active rTMS, approximately 10-15 min and then complete tasks and questionnaires.

Change in performance on a task assessing delay-discounting. Delay-discounting assesses the participants' impulsivity by requiring them to make choices between smaller sooner hypothetical money rewards and larger later hypothetical money rewards (e.g. $10 today vs $100 in a year). This is a hypothetical choice, and the participant will not be receiving the chosen rewards. A short preliminary version of the task will be completed at the start of the first session (prior to TMS) to optimize task parameters for each participant. The task will be completed on a laptop computer.

Change in performance on a task assessing reinforcement learning. The reinforcement learning task assesses how well participants learn from rewards vs. punishments. The task will ask participants to choose from two stimuli that predict reward (gaining points) or punishment (losing points) at different rates, which they will learn in the course of the task based on feedback. At the end of the task, participants will be asked to rate how well each stimulus predicted reward or punishment.

Change in impulse control disorder symptoms measured using a modified version of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS). QUIP-RS is a self-administered assessment of impulsive and compulsive behaviors in patients with PD. The QUIP-RS is a brief 28-item patient-reported or clinician-rated scale that was developed in PD and derived from the QUIP to measure of severity of ICDs. Each item is rated on a 5-point Likert scale assessing the frequency of symptoms with a range of scores from 0 (never) to 4 (very often).