Substance use disorders (SUDs) are characterized by disruption of brain circuits that support reward processing and goal-directed behavior. Across substances, converging evidence points to dysfunction within the anterior midcingulate cortex (MCC), a key node for reinforcement learning that uses reward prediction error signals to guide adaptive behavior. One electrophysiological index of this function—the reward positivity (RewP)—has provided important insight into how reward processing is altered in addiction and related conditions. However, translating this knowledge into effective interventions requires the ability to causally and precisely modulate this circuit. Transcranial magnetic stimulation (TMS) offers a powerful approach to probe and influence MCC function, but its efficacy depends critically on how stimulation is delivered. In this talk, I will present a framework for optimizing TMS along two key dimensions: targeting and pulse protocol. First, I will show that individualized targeting based on structural and functional connectivity between the dorsolateral prefrontal cortex (DLPFC) and MCC enables more precise engagement of the reward circuit. Second, I will demonstrate that stimulation frequency is not interchangeable: different pulse protocols produce distinct, and in some cases opposing, effects on MCC reward signaling as indexed by the RewP. Importantly, modulation of this signal is not epiphenomenal—it maps onto behavior. Enhancing MCC reward signaling is associated with improved reward learning and goal-directed behavior, whereas disrupting it produces the opposite pattern. These findings establish that TMS can bidirectionally modulate core reward computations relevant to addiction. Together, this work has led to the development of PRIME TMS (Pathway-precise Reward Intervention via MCC Engagement), a precision neuromodulation approach that integrates connectivity-guided targeting with optimized stimulation parameters to restore reward circuit function. By directly targeting the neural mechanisms underlying impaired motivation, PRIME TMS represents a scalable strategy for improving treatment outcomes in SUD and related disorders.