Spatial remapping of Tactile Events: Assessing the effects of frequent posture changes

Abstract

During the apparently mindless act of localizing a tactile sensation our brain must realign its initial spatial representation on the skin (somatotopicaly arranged) according to current body posture (arising from proprioception, vision and even audition). We have recently illustrated4 the temporal course of this recoding of tactile space from somatotopic to external coordinates using a crossmodal cueing psychophysical paradigm5,6 where behavioural reactions to visual targets are evaluated as a function of the location of irrelevant tactile cues. We found that the tactile events are initially represented in terms of a fleeting, non-conscious but nevertheless behaviorally consequential somatotopic format, which is quickly replaced by the representations referred to external spatial locations that prevail in our everyday experience. In this addendum, we test the intuition that frequent changes in body posture will make it harder to update the spatial remapping system and thus, produce stronger psychophysical correlates of the initial somatotopically-based spatial representations. Contrary to this expectation, however, we found no evidence for a modulation when preventing adaptation to a body posture.