Affiliations: [a]
Department of Psychology, University of Rome “La Sapienza, ” Via dei Marsi, Rome, Italy
| [b]
IRCCS Santa Lucia Foundation, Via Ardeatina, Rome, Italy
| [c]
Institute of Cognitive Neuroscience, University College London, London, UK
| [d]
Neuropsychology Unit, Department of Neurology, University Hospital Zurich, Switzerland
Correspondence:
[*]
Corresponding author: Mariella Pazzaglia, Dipartimento di Psicologia, Universitá di Roma “La Sapienza,” Via dei Marsi 78, 00185, Roma, Italia. E-mail: [email protected].
Abstract: Purpose: Spinal cord injury (SCI), a profound impairment of sensorimotor functions, is often associated with pain related phenomena, including mechanical allodynia, a condition in which non-painful tactile sensation is perceived as pain. Pain and somatic sensation are undeniable markers of normal bodily awareness. However, the mechanism by which they are integrated into a coherent sense of the bodily self remains largely unclear. In this study, we investigated the effect of high-level multisensory manipulation on subjective experiences of pain, touch, and body-ownership. Methods: We administered visuo-tactile stimulation based on the rubber hand illusion. In a longitudinal study, we compared the strength of the illusion in a male with SCI, who initially had lost somatosensation in all his fingers, but a few months later reported signs of tactile allodynia restricted to the left C6-dermatome. Results: After the restoration of some somatosensation, even if it were painful, synchronous but not asynchronous visuo-tactile stimulation induced body illusion. Previously painful stimuli were temporarily perceived as less painful, and the patient further regained tactile sensations in adjacent numb areas. Conclusions: The sensations of touch and pain are mutually influenced and inextricably linked to a coherent representation of one’s own body. Multisensory manipulations affecting the perception and representation of the body might thus offer a powerful opportunity to mitigate nociceptive and somatic abnormalities.
