Differential neuronal activity during perception of congruent and incongruent audiovisual motion

Oliver Baumann, University of Regensburg/Dep. for Experimental Psychology

Abstract
We investigated the cortical activations associated with coherent visual motion perception in the presence of a stationary or moving sound source. Twelve subjects judged 5s-episodes of random-dot motion containing either no (0%), meager (3%) or abundant (16%) coherent direction information. Simultaneously a moving auditory noise was presented. In a 4AFC response paradigm, subjects judged whether visual coherent motion was present, and if so, whether the auditory sound source was moving in-phase, was moving out-of-phase or was not moving. T2*-weighted images were acquired using a 1.5 T Siemens Sonata. To eliminate interference with the noises created by the gradient system, a sparse imaging design was employed. An SPM2 fixed-effects analysis revealed significant BOLD clusters in extrastriate and associational visual cortex that increased with visual coherence level. Auditory motion activated an extended region in the STG. Combined audio-visual motion led to significant activation in the supramarginal gyrus and STG and the effect size is larger with congruent movement direction. Our findings indicate that the lateral parietal and superior temporal cortex underlies our ability to integrate audio-visual motion cues.

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