Causative role of left aIPS in coding shared goals during human-Avatar complementary joint actions

Successful motor interactions require agents to anticipate what a partner is doing in order to predictively adjust their own movements. Although the neural underpinnings of the ability to predict others € action goals have been well explored during passive action observation, no study has yet clarified any critical neural substrate supporting interpersonal coordination during active, non-imitative (complementary) interactions. Here, we combine non-invasive inhibitory brain stimulation (continuous Theta Burst Stimulation) with a novel human-Avatar interaction task to investigate a causal role for higher-order motor cortical regions in supporting the ability to predict and adapt to others € actions. We demonstrate that inhibition of left anterior intraparietal sulcus (aIPS), but not ventral premotor cortex, selectively impaired individuals € performance during complementary interactions. Thus, in addition to coding observed and executed action goals, aIPS is crucial in coding € shared goals €, that is, integrating predictions about one € s and others € complementary actions.