Stimulating the posterior parietal cortex reduces self-reported risk-taking propensity in people with tobacco use...

Previous research has identified a replicable role for the posterior parietal cortex (PPC) in risk behaviors, but it is unclear whether this relationship is causal. Here, we used a targeted neuromodulation protocol leveraging a single-session of 10-Hz rTMS to the PPC versus a control region in the visual cortex (V5), as well as two active comparison regions [superior frontal gyrus (SFG), dorsolateral prefrontal cortex (DLPFC)] (within-person, randomized order), to examine within-session changes in a comprehensive measure of self-reported risk-taking propensity (the Domain-Specific Risk-Taking or DOSPERT scale). Individuals with tobacco use disorder were selected as sample participants who present with clinically relevant risk-taking propensity (N = 50; 14 women, mean [SE] age=33.1 [1.04] years). Results indicated that stimulating the PPC (versus V5) resulted in trend-level reductions in self-reported risk-taking propensity (region-by-time interaction, P = 0.065). A similar pattern emerged comparing PPC stimulation to effects of stimulating either the DLPFC (P = 0.080) or SFG (P = 0.032). PPC-related reductions in risk-taking propensity were domain general and potentially driven by changes in risk perception rather than perceptions of expected benefits of risk-taking. These findings support a possible causal role of the PPC in risk behaviors that warrants further consideration for therapeutic indications in conditions like tobacco use disorder.