Dynamic causal modeling analysis reveals the modulation of motor cortex and integration in superior temporal gyrus during multisensory speech perception

Abstract The processing of speech information from various sensory modalities is crucial for human communication. Both left posterior superior temporal gyrus (pSTG) and motor cortex importantly involve in the multisensory perception. However, dynamic integration primary regions to pSTG remain unclear. Here, we implemented a behavioral experiment classical McGurk effect paradigm acquired task functional magnetic resonance imaging (fMRI) data during synchronized audiovisual syllabic perception 63 normal adults. We conducted causal modeling (DCM) analysis explore cross-modal interactions among pSTG, precentral (PrG), middle (mSTG), fusiform (FuG). Bayesian model selection favored winning that included modulations connections PrG (mSTG → PrG, FuG PrG), (PrG mSTG, FuG), pSTG). Moreover, coupling strength above correlated with susceptibility. In addition, significant differences were found these between strong weak perceivers. Strong perceivers modulated less inhibitory visual influence, allowed excitatory auditory flowing into but integrated more pSTG. Taken together, our findings show interact dynamically cortices speech, support plays specifically role modulating gain salience modalities.