Neural Mechanisms of Bidirectional Visuo-Linguistic Transformation in Interactive Communication

Human communication requires the flexible transformation of visual input into verbal descriptions and the reconstruction of mental imagery from language. However, the neural mechanisms underlying these bidirectional transformations during social interaction remain poorly understood. Using hyperscanning fMRI and a role-switching communicative task, we investigated how individuals alternately encode visual stimuli into language and decode language into mental imagery within an interactive context. Whole-brain analyses identified brain regions implicated in these processes. Based on these findings, we selected three key regions-the inferior frontal gyrus (IFG), fusiform face area (FFA), and intraparietal sulcus (IPS)-and applied dynamic causal modeling (DCM) to examine their effective connectivity. The DCM results revealed that connectivity among IFG, FFA, and IPS dynamically reconfigures to support role-dependent shifts between top-down and bottom-up information flow. These findings highlight a flexible, coordinated neural architecture that integrates visual and linguistic information, offering new insights into how communication arises from the interplay between perceptual and language systems.