Emotional and Social Dimension of Abstract Concepts Meet with Interoception in Right Anterior Insula.

According to the embodied cognition theory, which claims that concepts' representation is grounded in sensory and motor components, abstract concepts are grounded in interoception, which is processed in the Anterior Insula (AIns). However, it is not clear whether interoception and abstract concepts share common anatomical substrates, and if yes, whether AIns is one candidate. In this study, we used repetitive transcranial magnetic stimulation (rTMS) on healthy human participants (N = 25, 19 females) to examine whether left and right AIns play a role in both abstract concepts and interoception. The heartbeat counting task served as a measure of interoceptive accuracy, and the semantic similarity judgment as a measure of semantic performance. Concepts were characterized according to both a categorical approach, contrasting three categories of concepts, namely social and emotion (abstract categories) and objects (concrete category), and a dimensional approach, collecting semantic ratings on the emotion and social dimensions of abstract and concrete concepts. TMS site and TMS-induced electric field inside the AIns ROI were used to predict interoceptive and semantic behavioral responses. Both TMS site and E-field ROI analyses confirmed the right AIns' role in supporting interoception and the emotion and social dimensions of abstract concepts. This aligns with an embodied cognition framework, where AIns is involved in both the nonlinguistic and linguistic processing of emotional and social dimensions. Together, these results support the evidence of a relation between interoception and socio-emotional semantics and the convergence of these two processes on the right AIns.