Auditory areas are activated during a visuo-motor task

Roberto Martuzzi, Department of Radiology, University Hospital, Lausanne, Switzerland

Abstract
Evidence is accumulating that brain regions traditionally considered as unisensory contribute to multisensory interactions. In this study, we investigated the BOLD response within auditory areas during a visuo-motor task. Ten subjects performed a simple reaction-time task in response to a lateralized visual stimulus at 1.5T. Stimuli were randomly presented at the right or at the left visual field (lateralization 9.5°), and subjects were asked to respond upon simple detection with the right hand in the first session and with the left one during the second session. Stimuli were presented for 125ms with and inter-trial interval varying from 14.125 to 17.875s in steps of 125ms. In addition to activations within visual- and motor-related areas, we identified frank bilateral activations within auditory areas, with a clear predominance (both in size and in intensity) on the side contralateral to the responding hand. This dominance suggests that the signal intensity is primarily modulated by the responding hand and/or by the somatosensory stimulation generated during the motor response. The visual field of stimulation did not directly impact response size or intensity. The collective findings raise the possibility that activations in auditory cortices during visuo-motor tasks are more related to auditory-somatosensory interactions than to auditory-visual interactions.

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