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You or me? Case study published in Cortex

© LNCO / 2019 EPFL

© LNCO / 2019 EPFL

Michela Bassolino and colleagues' recent case study entitled "You or me? Disentangling perspectival, perceptual, and integrative mechanisms in heterotopagnosia" has been published in Cortex. The results offer a new interpretation of Heterotopagnosia-without-Autotopagnosia (HwA), which is characterized by the incapacity to point to body parts on others, but not on one's own body, 

In close collaboration with clinicians at the Clinique Romande de Réadaptation (Sion), Michela Bassolino and colleagues conducted a study with a patient showing a rare body-related disorder, classically called heterotopagnosia. Using a virtual reality study paradigm, the Blanke lab team was able to demonstrate that a deficit in matching somatosensory stimuli from one's own body with visual bodily stimuli of a body with different perspectival and other spatial attributes is the core deficit in HwA. VR technology was integral to demonstrating this matching process as it allowed systematically dissociating identity as well as the perspectival and spatial congruency between cues from own and other bodies. This work thus strongly encourages the use of VR protocols for the assessment and potential treatment of body-related disorders.

Abstract

Heterotopagnosia-without-Autotopagnosia (HwA) is characterized by the incapacity to point to body parts on others, but not on one's own body. This has been classically interpreted as related to a self-other distinction, with impaired visual representations of other bodies seen in third person perspective (3PP), besides spared own body somatosensory representations in 1PP. However, HwA could be impacted by a deficit in the integration of visual and somatosensory information in space, that are spatially congruent in the case of one's own body, but not for others' body.

Here, we test this hypothesis in a rare neurological patient with HwA, H+, as well as in a control patient with a comparable neuropsychological profile, but without HwA, and in age-matched healthy controls, in two experiments. First, we assessed body part recognition in a new task where somatosensory information from the participant's body and visual information from the target body shown in virtual reality was never aligned in space. Results show that, differently from the flawless performance in controls, H+ committed errors for not only the body of others in 3PP, but for all conditions where the information related to the real and the target body was not spatially congruent.

Then, we tested whether the integration between these multisensory bodily cues in space, as during visuo-tactile stimulation in the full-body illusion, improves the patient's performance. Data show that after the stimulation prompting visuo-tactile integration, but not in control conditions, the patient's abilities to process body parts improved up to normal level, thus confirming and extending the first findings. Altogether, these results support a new interpretation of HwA as linked to the matching between somatosensory inputs from one's body and visual information from a body seen at a distance, and encourage the application of multisensory stimulation and virtual reality for the treatment of body-related disorders.

Funding

Support for this study was provided by the Swiss National Science Foundation, Ambizione grant to MB (PZ00P1_161210) and the Bertarelli Foundation.

References

Bassolino, M., Bouzerda-Wahlen, A., Moix, V., Bellmann, A., Herbelin, B., Serino, A., & Blanke, O. (2019). You or me? Disentangling perspectival, perceptual, and integrative mechanisms in heterotopagnosia. Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, 120, 212‑222. https://doi.org/10.1016/j.cortex.2019.05.017 


Author: Oliver Kannape