Psychophysics & Neuroimaging Studies of the Multisensory Temporal Binding Window

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DESCRIPTION (provided by applicant): The brain's ability to bind incoming auditory and visual stimuli depends critically on the temporal structure of this multisensory information. Specifically, there exists a temporal window of audiovisual integration within which stimuli are bound and consequently processed as a unitary perceptual event. Although previous work has shown that this multisensory temporal window is somewhat task-and context-dependent, there is general agreement that the size of the window is on the order of several hundred milliseconds. Furthermore, more recent work has demonstrated a malleability of this temporal window by showing that repeated presentations of asynchronous auditory-visual pairings can shift its boundaries. Although this work highlights that the window can be shifted in time to reflect recent sensory experience, no studies have examined whether the size of the window can be altered. In the current proposal, we seek to examine this issue, which is framed around two specific aims. First, using a perceptual training paradigm, we will seek to shorten the size of the multisensory temporal window. Second, using fMRI, we will examine the neural basis of this temporal binding process and how the identified networks change with changing window size. To accomplish these aims, we will use an audiovisual simultaneity task to delineate the size of the temporal window. Next, we will develop a simultaneity judgment training paradigm wherein each judgment is paired with feedback as to its correctness. It is our expectation that this training paradigm will result in a significant narrowing of the temporal binding window, and, perhaps more importantly, that these effects will extend to other measures of multisensory temporal function (i.e., they will generalize). We have already gathered exciting preliminary data in support of a significant narrowing of the multisensory temporal binding window for simultaneity judgments. In addition, these effects appear to generalize to other tasks and to be long-lasting. What's more, in a preliminary data set, we have highlighted brain areas that appear to be altered after multisensory perceptual training. These studies will help to better define the plastic capacity of multisensory temporal processes in adults and their neural underpinnings, work that we hope will form a foundation for future remediation programs targeted toward neurobiological disorders (e.g., dyslexia, autism) in which there is growing evidence of disruptions in multisensory temporal function.