Neural Correlates of Vowel Perception Modulated by Audio-visual Asynchrony
Date Issued
2011
Date
2011
Author(s)
Chen, Chiao-Yu
Abstract
Intersensory temporal synchrony is critical in multisensory integration. Human brain has the ability to combine information from different sense modalities as a unified perception when stimuli are presented with a minor temporal latency . For example, we have congruent speech perception even though auditory (heard speech) and visual (lip-reading) stimuli are sent through different physical mechanisms and speeds. Little is known about how brain detects temporal asynchrony between audiovisual stimuli. To study where in the brain is sensitive to asynchrony of audio-visual speech and associated with vowel processing, we presented vowel sounds and short video clips of the articulatory gestures with three audio-visual latencies, which are simultaneous, asynchronous inside the window of temporal integration, and asynchronous outside the temporal integration. Based on the BOLD-contrast fMRI from11 participants, we found that the bilateral superior temporal gyri have stronger activation when the audio-visual stimulus latency increase. The left insula is more significantly activated by asynchronous audio-visual stimuli with latency inside the integration window than simultaneous stimuli. Not only the insula but also bilateral superior temporal gyri are activated significantly when audio-visual stimuli are asynchrous with a latency outside the integration window. These results suggest that bilateral superior gyri and left insula integrate the lagged auditory stimuli to the visual stimuli, and the left insula is more sensitive to the temporal the asynchrony of audio-visual speech than bilateral gyri.
Subjects
audiovisual
functional magnetic resonance imaging
multisensory integration
temporal
insula
superior temporal gyrus
vowel
Type
thesis
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