What can errors tell us about body representations?

Abstract

After an organism is touched, various processes need to occur to accurately localize touch on the body. In this review, we examine how tactile misperceptions can provide evidence regarding the functional organization of body representations. First, we propose that tactile detection and localization are serial processes, in contrast to hypotheses that propose separable parallel processes based on patients with numbsense. Second, we discuss how information in primary somatosensory maps project to representations of body size and shape (body form) in order to localize touch on the skin surface. Using this as a framework, we examine how responses after use-dependent plasticity reflect changes in this mapping, and propose potential mechanisms that could be used minimize tactile localization error in conditions with increased sensory uncertainty. Third, we review situations in which our representation of body form is inconsistent with our actual body shape, specifically discussing phantom limb phenomena and alterations of perceived body size and shape in normal individuals. We discuss problems with the traditional remapping hypothesis of referred sensations in amputees, factors that modulate our perception of body size and shape, and how changes in perceived body form influence tactile localization. Finally, we review studies in which brain-damaged individuals perceive touch on the opposite side of the body, and demonstrate how interhemispheric mechanisms can give rise to these anomalous percepts.

Explicit and Implicit Own's Body and Space Perception in Painful Musculoskeletal Disorders and Rheumatic Diseases: A Systematic Scoping Review

“…Every deviation from the published protocol (Viceconti et al, 2018) or added procedure were declared. Neuroscientists (ML, AG, MP) and physiotherapists (AV, DL, DP, DR, GR, MT) constituted an inter-professional and interdisciplinary research team with both clinical and scientific background to better approach, from a rehabilitative perspective, a research area that has been historically treated by neuropsychological disciplines (Head and Holmes, 1911;Haggard and Wolpert, 2005;Medina and Coslett, 2016b). In agreement with the concept of a "literature map, " the results are graphically presented in Figures 3-8.…”

“…Substantial differences exist between the two high-order processes represented by the somatoperception and somatorepresentation, from the basics mechanisms of the somatosensations . Despite these three different mechanisms are integrated and linked (Moseley et al, 2012), they may be dissociable, at least partially, because each one is based on different functional and neuroanatomical underlying structures and mechanisms: see for a review on the neural bases of body representations and Medina and Coslett (2016b) for descriptions of clinical cases highlighting this dissociation.…”

“…Notably, pain and body perception are essentially two subjective mutually influencing perceptual experiences Trojan et al, 2014): the fast and accurate perception of pain is essential to protect the body, and the perception of body integrity is needed to avoid pain . Thus, the study of errors in processing the explicit (conscious) and implicit (unconscious) body experience, as in the case of illusion phenomena (Medina and Coslett, 2016b), may represent a useful opportunity to understand how the brain constructs functional representations of the body in patients with MDRDs, and on pain perception itself (Pamment and Aspell, 2017;Fang et al, 2019) in these clinical conditions. However, existing studies on SoP, SpP, and BO were largely conducted on healthy subjects (Longo et al, 2008a;Fuentes et al, 2013;Longo, 2017), and clinical research has mostly investigated neurological conditions (Haggard and Wolpert, 2005;Pia et al, 2013Pia et al, , 2016, eating disorders (Keizer et al, 2011;Scarpina et al, 2014;Spitoni et al, 2015;Gadsby, 2017), and neuropathic pain syndromes such as Complex Regional Pain Syndrome-CRPS (Galer and Jensen, 1999;Förderreuther et al, 2004;Lewis et al, 2007;Reinersmann et al, 2013).…”

Understanding body representations

“…This approach is adopted by several contributors to this issue. Medina and Coslett (2016) examine how errors in tactile perception inform us regarding how the brain represents the body. First, they discuss whether participants with numbtouchwho are thought to be able to localize touch without feeling touchprovide evidence in support of a double dissociation between processes for tactile detection and localization.…”

Implied tactile motion: Localizing dynamic stimulations on the skin

“…Interestingly, even the localization of static, tactile events (e.g., a tap on the skin) is not always error-free. It has, for example, often been reported that a static tactile stimulus may be systematically misperceived at a different spatial location (Harrar & Harris, 2009;Ho & Spence, 2007;Longo, 2017;Mancini, Longo, Iannetti, & Haggard, 2011;Margolis & Longo, 2015;Steenbergen, Buitenweg, Trojan, & Veltink, 2014;Trojan et al, 2006; see Medina & Coslett, 2016, for a discussion). Even on the hand and fingers, locations that are very sensitive to two-point discrimination and localization (see Gallace & Spence, 2014;Stevens & Choo, 1996;Weinstein, 1968), systematic mislocalizations have been documented (e.g., Mancini et al, 2011;Margolis & Longo, 2015).…”