title: Where are my hands? Influence of limb posture on tactile extinction.
abstract: OBJECTIVE
  Tactile localization on the skin involves both a somatotopic and a postural schema (body-schema) representation. The present study determines the extent to which body posture influences tactile perception in right-brain-damaged patients.
  
  
  METHODS
  In a first set of experiments, patients were asked to detect single tactile stimulation delivered to their left or right hands or to both hands simultaneously (double stimulation) in different arm postures. Only patients who had no difficulty localizing single and double tactile stimulations when their hands were placed in anatomic position were tested. Participant's hands were crossed, one over the other, and the tactile stimuli were delivered either to the hand (beyond the crossing point, Experiment 1) or to the forearm (before the crossing point, Experiment 2). In Experiment 3, the left hand was placed in the right hemispace and the right hand in the left hemispace without crossing over (opposite condition). In a second set of experiments, patients were asked to detect stimulation delivered to the forefinger. The fingers were crossed, one over the other at the level of the middle phalanx, and stimuli were delivered either beyond or before the crossing point.
  
  
  RESULTS
  In all experimental conditions, control participants performed at ceiling. We observed a left-hand tactile extinction on double stimulation in the crossed condition.
  
  
  CONCLUSIONS
  These results suggest that tactile stimuli can be encoded based on multiple specific body-part representations rather than on an integrated body-schema representation.
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, INSERM U663, Paris, France. laurent.auclair@parisdescartes.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Auclair
authors.forename: Julien
authors.initials: J
authors.lastname: Barra
authors.forename: Patrick
authors.initials: P
authors.lastname: Raibaut
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000150:complications*; D005108:Extinction, Psychological; D005260:Female; D005385:Fingers / Q000294:innervation; D005542:Forearm / Q000294:innervation; D007839:Functional Laterality; D006225:Hand / Q000294:innervation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010468:Perceptual Disorders / Q000175:diagnosis / Q000209:etiology*; D010812:Physical Stimulation; D011187:Posture / Q000502:physiology*; D017603:Signal Detection, Psychological / Q000502:physiology; D018709:Statistics, Nonparametric; D014110:Touch / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology; D055815:Young Adult