Similar physiological mechanisms for integrating somatotopic and body-centred frames of reference underlie the ability to determine the spatial location of both nociceptive and tactile stimuli.
Crossing the hands over the midline impairs the ability to correctly judge the order of a pair of tactile stimuli, delivered in rapid succession, one to each hand. This impairment, termed crossed-hands deficit, has been attributed to a mismatch between the somatotopic and body-centred frames of reference, onto which somatosensory stimuli are automatically mapped. Whether or not such crossed-hands deficit occurs also when delivering nociceptive stimuli has not been previously investigated. In this study, participants performed a temporal order judgement (TOJ) task in which pairs of either nociceptive or tactile stimuli were delivered, one to each hand, while their arms were either crossed over the body midline or uncrossed. We observed that crossing the hands over the midline significantly decreases the ability to determine the stimulus order when a pair of nociceptive stimuli is delivered to the hands, and that this crossed-hands deficit has a temporal profile similar to that observed for tactile stimuli. These findings suggest that similar mechanisms for integrating somatotopic and body-centred frames of reference underlie the ability to localise both nociceptive and tactile stimuli in space.
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a Department of Neuroscience, Physiology and Pharmacology, University College London, UK
b Department of Psychology, City University London, UK
c Department of Psychology, University of Turin, Italy
d Department of Psychology, University of Milano-Bicocca, Italy
e Neuroscience Research Australia, Sydney, Australia
f Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
*Corresponding authors. Addresses: Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK. Tel.: +44 (0) 20 7679 2156 (C.F. Sambo), Department of Psychology, University of Turin, Via Po 14, 10123 Turin, Italy. Tel.: +39 (0) 116703924 (D.M. Torta).
1These authors contributed equally to this work, and both should be considered first author.
Submitted April 17, 2012; revised August 16, 2012; accepted October 18, 2012.