Spatial Alignment of the Senses: The Role of Audition in Eye-Hand-Coordination

Sensory modalities are usually appropriately aligned in space: audition, vision, and proprioception each direct actions to the same spatial coordinates. Subjects wearing prism glasses that shift the visual input first miss the target in a pointing task, but quickly adapt to the new sensorimotor configuration. This adaptation may take place either in the visual or the proprioceptive pathway, ie, the internal visual representation is shifted back or the proprioceptive one is shifted towards the new configuration. Usually, the proprioceptive component is affected, probably due to the often observed dominance of vision over other modalities. This process is changed when auditory stimuli are presented during prism exposure inducing a shift of the visual representation contrary to the aforementioned results, maybe because a cortical mechanism performs statistical reliability estimation: Both audition and proprioception remain unaffected by prism exposure and therefore force vision to realign. We investigated the influence of sound-source-location on prism-adaptation by assessing the effects of displaced (accordingly to the prism offset), centered and unlocalized sound-sources. We discuss the influence of spatial properties on sensory calibration, its implications on the notion of motor action as the binding element between senses and its role in spatial adaptation processes.