Sensory processing dysfunction is characterized by a behaviorally observed difference in the response to sensory information from the environment. While the cerebellum is involved in normal sensory processing, it has not yet been examined in SPD. Diffusion tensor imaging scans of children with SPD and typically developing controls were compared for fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity across the following cerebellar tracts: the middle cerebellar peduncles, superior cerebellar peduncles, and cerebral peduncles. Compared to TDC, children with SPD (...) show reduced microstructural integrity of the SCP and MCP, characterized by reduced FA and increased MD and RD, which correlates with abnormal auditory behavior, multisensory integration, and attention, but not tactile behavior or direct measures of auditory discrimination. In contradistinction, decreased CP microstructural integrity in SPD correlates with abnormal tactile and auditory behavior and direct measures of auditory discrimination, but not multisensory integration or attention. Hence, altered cerebellar white matter organization is associated with complex sensory behavior and attention in SPD, which prompts further consideration of diagnostic measures and treatments to better serve affected individuals. (shrink)

The McGurk illusion occurs when listeners hear an illusory percept, resulting from mismatched pairings of audiovisual speech stimuli. Hearing a third percept—distinct from both the auditory and visual input—has been used as evidence of AV fusion. We examined whether the McGurk illusion is instead driven by visual dominance, whereby the third percept, e.g., “da,” represents a default percept for visemes with an ambiguous place of articulation, like/ga/. Participants watched videos of a talker uttering various consonant vowels with and without audios (...) of/ba/. Individuals transcribed the CV they saw or heard. In the V-only condition, individuals predominantly saw “da”/“ta” when viewing CVs with indiscernible POAs. Likewise, in the AV condition, upon perceiving an illusion, they predominantly heard “da”/“ta” for CVs with indiscernible POAs. The illusion was stronger in individuals who exhibited weak/ba/auditory encoding. In Experiment2, we attempted to replicate these findings using stimuli recorded from a different talker. The V-only results were not replicated, but again individuals predominately heard “da”/“ta”/“tha” as an illusory percept for various AV combinations, and the illusion was stronger in individuals who exhibited weak/ba/auditory encoding. These results demonstrate that when visual CVs with indiscernible POAs are paired with a weakly encoded auditory/ba/, listeners default to hearing “da”/“ta”/“tha”—thus, tempering the AV fusion account, and favoring a default mechanism triggered when both AV stimuli are ambiguous. (shrink)