The spatial encoding of body parts in patients with neglect and neurologically unimpaired participants

Ambra V. Sposito, Nadia Bolognini, Giuseppe Vallar, Lucio Posteraro, Angelo Maravita

Research output: Contribution to journalArticle

Abstract

Body parts are represented in the brain in a very specific fashion, as compared to other three-dimensional objects, with reference to their prototypic shape and multisensory coding. However, evidence is lacking about the spatial representation of body parts. To address this issue, in Experiment 1 we first compared the metric representation of body parts and of non-bodily objects in 14 right-brain-damaged patients with left unilateral spatial neglect (USN), and in 14 neurologically unimpaired control participants. Participants bisected, by manual pointing, a three-dimensional object, or their own left forearm. Patients showed the well-known ipsilesional rightward displacement of the subjective midpoint, in both forearm and solid bisection. Both USN patients and control participants were overall more accurate in the bisection of their own forearm, relative to the extracorporeal object. In four patients this advantage of the forearm was significant in a single-case analysis, while two patients showed the opposite dissociation, being more accurate with the solid object. In Experiment 2 neurologically unimpaired participants were more accurate in the bisection of a fake forearm, as well as of their own forearm, as compared to the extrapersonal object. Overall, the results indicate that the representation of the metric of the body is more reliable than that of extrapersonal objects, and also more resistant to the disruption of spatial representations brought about by USN, possibly due to the prototypical shape of body parts. Furthermore, the double dissociation found in USN patients suggests that the metrics of body parts and of extrapersonal objects are supported by independent spatial processes.

Original languageEnglish
Pages (from-to)334-340
Number of pages7
JournalNeuropsychologia
Volume48
Issue number1
DOIs
Publication statusPublished - Jan 2010

Keywords

  • Body representation
  • Multisensory integration
  • Space coding
  • Spatial impairments
  • Unilateral spatial neglect

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Cognitive Neuroscience
  • Experimental and Cognitive Psychology

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