Abstract
Perceived upright depends on three main factors: vision, graviception, and the internal representation of the long axis of the body. We assessed the relative contributions of these factors in individuals with sub-acute and chronic stroke and controls using a novel tool; the Oriented Character Recognition Test (OCHART). We also considered whether individuals who displayed active pushing or had a history of pushing behaviours had different weightings than those with no signs of pushing. Three participants experienced a stroke 6 months prior: eight with a history of pushing. In total, 12 participants served as healthy aged-matched controls. Visual and graviceptive cues were dissociated by orienting the visual background left, right, or upright relative to the body, or by orienting the body left, right, or upright relative to gravity. A three-vector model was used to quantify the weightings of vision, graviception, and the body to the perceptual upright. The control group showed weightings of 13% vision, 25% graviception, and 62% body. Some individuals with stroke showed a similar pattern; others, particularly those with recent stroke, showed different patterns, for example, being unaffected by one of the three factors. The participant with active pushing behaviour displayed an ipsilesional perceptual bias (>30°) and was not affected by visual cues to upright. The results of OCHART may be used to quantify the weightings of multisensory inputs in individuals post-stroke and may help characterize perceptual sources of pushing behaviours.
Highlights
RÉSUMÉ: Le poids des repères impliqués dans la perception de la verticalité chez des patients atteints d’un AVC ayant ou non des antécédents de latéropulsion
Two of the chronic stroke participants with a history of pushing (HP) behaviour had contralesional biases that were outside the range of the healthy controls (−12.6 and −4°, respectively) and as a group overall, the HP chronic stroke participant group had a significant contralesional bias in SVV, but the no recorded history of pushing (NHP) group did not (Z = 9.0, p = 0.69).[5]
More research is needed to confirm whether these results are typical of other individuals with active pushing (AP), as our findings indicate some individuals with a HP have a bias in SVV that lingers after overt pushing behaviours have resolved.[5]
Summary
RÉSUMÉ: Le poids des repères impliqués dans la perception de la verticalité chez des patients atteints d’un AVC ayant ou non des antécédents de latéropulsion. Nous avons aussi cherché à savoir si les patients montrant des signes de latéropulsion active ou ayant des antécédents de latéropulsion accordaient un poids différent aux repères de la perception de la verticalité, et ce, en comparaison avec ceux ne montrant aucun signe de latéropulsion. Méthodes: Trois participants avaient été atteints d’un AVC moins de 3 mois avant la réalisation de cette expérience, dont un montrant des signes de latéropulsion active. Certains patients atteints d’AVC ont montré un profil similaire ; d’autres, particulièrement ceux récemment victimes d’un AVC, ont présenté des profils différents, n’étant pas, par exemple, affectés par un de ces trois facteurs. Cet outil pourrait également permettre de mieux caractériser les causes perceptuelles liées à la latéropulsion
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Schedule a callMore From: The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques
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