Functional specialization of the human posterior parietal cortex in visually and proprioceptively driven reaching corrections

While online adjustments during reaching are essential for interacting with our dynamic environment,the specialized contributions of subregions of the posterior parietal cortex (PPC) remain unclear. In thisstudy, we investigate the distinct roles of human medial PPC areas V6A (hV6A) and PEc (hPEc) inmediating online reaching corrections elicited by visual and proprioceptive perturbations. Here wedeliver online repetitive transcranial magnetic stimulation (rTMS) during the early stages of reachingcorrections triggered by an unexpected shift of the visual target or by the application of an externalforce to the wrist. Our findings reveal that rTMS over hV6A selectively impairs the ability to correctreach trajectories for visual perturbations, whereas stimulation of hPEc interferes only withproprioceptively driven corrections. These findings confirm the critical role of hV6A in processingvisual feedback, demonstrate the causal involvement of hPEc in integrating proprioceptiveinformation to guide motor adjustments, and show how the PPC selectively engages specializedneural circuits to adapt motor control strategies according to the sensory nature of thereaching perturbation.