Neural correlates of visual and audio-visual perception using functional magnetic resonance imaging (fMRI)
Abstract
In daily life human beings receive data from the outside world through multiple sensory organs. Humans form perception of the external world through selective processing of portions of these data. Among the many perceptions obtained, visual and audio-visual perceptions are arguably the most crucial to daily life. In the first study described here, an investigation was made of the neural correlates underlying visual motion perception of the novel phi-phenomenon (discovered by Max Wertheimer, who launched the Gestalt revolution). The result of this investigation contributes to existing models of human visual motion perception. The second study herein examines how, as social animals, normal-hearing people integrate auditory and visual cues to enhance speech recognition. Greater enhancement of the recognition resulting from audio-visual integration may be of significant benefit to profoundly hearing-impaired individuals who use sign language (effectively visual speech) or cochlear implants. This latter work is partially motivated by the knowledge that, although the sound provided by a cochlear implant is heavily degraded and may be incomprehensible in isolation, the device is known to provide some (albeit variable) benefit to spoken language recognition. In particular, this second study uses normal-hearing subjects presented with degraded auditory speech stimuli to search for the underlying neural circuitry recruited to enhance spoken language recognition in the presence of visual cues. The results of this study may be used for pre-surgical screening of individuals who will best experience such audio-visual integration benefits. In the aggregate, these two studies will enhance our understanding of brain mechanisms for perception of visual motion and audio-visual speech and contribute to the development of medical prostheses for vision-impaired and hearing-impaired individuals.
Degree
Ph.D.
Advisors
Talavage, Purdue University.
Subject Area
Electrical engineering
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