OVERT AND COVERT ORIENTING TO COMBINED AUDIO-VISUAL STIMULI

Douglas Munoz, Centre for Neuroscience Studies, Queen's University

Abstract
D. P. Munoz and A. H. Bell

Recent neurophysiological evidence shows a clear role for the superior colliculus (SC) in reflexive covert orienting. In a standard visual cueing task, a cue is presented somewhere in the visual field in advance of the target. The cue can be located at the same location as the target or elsewhere, and it can sometimes reliably predict upcoming target location. In these tasks, modified sensory processing in the SC is correlated with both reflexive attention capture and subsequent inhibition of return: attention capture is correlated with an augmented sensory response to the target and inhibition of return is correlated with a reduction in magnitude of the sensory response. When the cue reliably predicts upcoming target location, top-down influences can modify SC activity in advance of target presentation to then influence sensory processing of the target. Previous reports have described conflicting results in auditory cueing tasks, with some studies producing reliable behavioural effects with auditory cues and others failing to produce effects. The Munoz lab has generated new neurophysiological evidence in the SC showing why cueing effects for auditory and visual stimuli produce such different influences on behavior.

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