Toward an Iterative, Testable Transcranial Magnetic Stimulation Framework for Posttraumatic Stress Disorder
Abstract
Transcranial magnetic stimulation (TMS) has shown promise as a treatment for posttraumatic stress disorder (PTSD); however, the field continues to face a deceptively simple question: where should stimulation be delivered? Existing studies have targeted the left dorsolateral prefrontal cortex (DLPFC), right DLPFC, medial prefrontal regions, and other cortical sites using a range of frequencies, pulse patterns, coils, and treatment schedules (1). This variation has generated encouraging findings, yet with substantial heterogeneity, which may make it tempting to attribute inconsistent outcomes to the absence of a single correct target. That said, target location is one component of a broader problem involving symptom heterogeneity, stimulation parameters, comorbidity, treatment context, and the biological dose received by each patient. In a recent study published in Biological Psychiatry: Global Open Science , Chandrashekar et al. (2) provide an important framework for approaching that problem. Using clinical and neuroimaging data from 350 post-9/11 service members and veterans in the Translational Research Center for TBI and Stress Disorders (TRACTS) cohort (3), the authors combined whole-brain resting-state functional connectivity, dimensional PTSD symptom severity, and individualized electric-field modeling. They simulated TMS at 200 cortical sites per participant and estimated how connectivity changes proportional to the modeled electric field might influence PTSD symptoms. These predictions were then projected across the cortical surface to produce a whole-brain TMS atlas. Two broad patterns emerged: stimulation expected to increase connectivity in left prefrontal and anterior temporal regions was predicted to reduce symptoms, whereas stimulation expected to decrease connectivity in bilateral occipital and posterior parietal regions was also predicted to be beneficial. The importance of this work lies in establishing a roadmap for target discovery. The