Audio-visual crossmodal connectivity in perceiving distorted speech: A comparison between patients with cleft palate and typical listeners.

This study investigates audio-visual crossmodal connectivity during the perception of distorted speech using task-based functional magnetic resonance imaging (fMRI). A randomized block design was employed, involving 20 patients with cleft palate and 20 typical listeners. Participants underwent perceptual tasks involving both cleft-related glottal stop and typical speech while fMRI scans were conducted. Regional interactions between the auditory and visual cortices were analyzed using dynamic causal modeling (DCM). Individual-level effective connectivity analysis revealed that, during the perception of glottal stop, patients with cleft palate exhibited significantly reduced effective connectivity from the left superior temporal gyrus to the left inferior occipital gyrus compared to typical listeners (p = 0.035). However, no significant difference was observed in the connectivity weights from the right superior temporal gyrus to the right inferior occipital gyrus. These findings suggest a potential deficit in audio-visual integration in patients with cleft palate, which may adversely affect speech perception. This insight advances our understanding of the neural mechanisms underlying speech disorders in cleft palate, particularly the contribution of crossmodal connectivity to speech processing.