Long Lasting Egocentric Disorientation Induced by Normal Sensori-Motor Spatial Interaction

Perception of the cardinal directions of the body, right-left, up-down, ahead-behind, which appears so absolute and fundamental to the organisation of behaviour can in fact, be modified. Perhaps unsurprisingly, it has been shown that prolonged distorted perception of the orientation of body axes can be a consequence of disordered sensori-motor signals, including long-term prismatic adaptation and lesions of the central nervous system. We report the novel and surprising finding that a long-lasting distortion of perception of personal space can also be induced by an ecological pointing task without the artifice of distorting normal sensori-motor relationships.Twelve right-handed healthy adults performed the task of pointing with their arms, without vision, to indicate their subjective 'straight ahead', a task often used to assess the Egocentric Reference. This was performed before, immediately, and one day after a second task intended to 'modulate' perception of spatial direction. The 'modulating' task lasted 5 minutes and consisted of asking participants to point with the right finger to targets that appeared only in one (right or left) half of a computer screen. Estimates of the 'straight-ahead' during pre-test were accurate (inferior to 0.3 degrees deviation). Significantly, up to one day after performing the modulating task, the subjective 'straight-ahead' was deviated (by approximately 3.2 degrees) to the same side to which subjects had pointed to targets.These results reveal that the perception of directional axes for behaviour is readily influenced by interactions with the environment that involve no artificial distortion of normal sensori-motor-spatial relationships and does not necessarily conform to the cardinal directions as defined by the anatomy of orthostatic posture. We thus suggest that perceived space is a dynamic construction directly dependent upon our past experience about the direction and/or the localisation of our sensori-motor spatial interaction with environment

Flexibility of the cognitive system to use various spatial coding : Implication for driving situation

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Research Proposal Bruel Léa

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Asymétrie et plasticité de la perception spaciale (étude de l'adulte sain et cérébro-lésé)

GRENOBLE2/3-BU Droit/Lettres (384212101) / SudocSudocFranceF

Spatial bias induced by a non-conflictual task reveals the nature of space perception

The aim of the present study was to show that space perception depends on sensori-motor experience. We induced spatial biases by a non-conflictual lateralized sensori-motor task on twenty seven right-handed healthy volunteers (left-to-right readers). After a pre-test and before a post-test, which assessed visuo-motor and perceptual subjective midpoint in line bisection, participants performed a short lateralized pointing task (towards the left or right hemispace). Results indicated that this lateralized pointing task induced deviations towards the stimulated hemispace in both the visuo-motor and the perceptual estimations of the subjective line centre. These spatial biases varied as a function of pointing direction (left or right pointing), spatial location and line lengths. These findings suggest that a preceding non-conflictual lateralized sensori-motor experience influences subsequent space perception. Accordingly, ecological sensori-motor experience could be involved in asymmetric perception exhibited by normal individuals and neglect patients

Induction of lateralized spatial bias among normal subjects

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Multimodal virtual reality application for the study of unilateral spatial neglect

In the present paper, we describe a virtual reality application developed for the study of unilateral spatial neglect, a post-stroke neurological disorder that results in failure to respond to stimuli presented contralaterally to the damaged hemisphere. Recently, it has been proposed that patients with unilateral spatial neglect experience sensorimotor decorrelation in the affected space. Consequently, it is possible that since the sensorimotor experience in the affected space is perturbed, patients avoid this space, which results in neglect behavior. Here, we evaluate this hypothesis using a virtual reality application built on the base of the Stringed Haptic Workbench, a large-scale visuo-haptic system. The results provide support for the hypothesis and demonstrate that the proposed application is suitable for the envisioned goal

Uses of virtual reality for diagnosis, rehabilitation and study of unilateral spatial neglect: review and analysis

International audienceUnilateral spatial neglect is a disabling condition frequently occurring after stroke. People with neglect suffer from various spatial deficits in several modalities, which in many cases impair everyday functioning. A successful treatment is yet to be found. Several techniques have been proposed in the last decades, but only a few showed long-lasting effects and none could completely rehabilitate the condition. Diagnostic methods of neglect could be improved as well. The disorder is normally diagnosed with pen-and-paper methods, which generally do not assess patients in everyday tasks and do not address some forms of the disorder. Recently, promising new methods based on virtual reality have emerged. Virtual reality technologies hold great opportunities for the development of effective assessment and treatment techniques for neglect because they provide rich, multimodal, and highly controllable environments. In order to stimulate advancements in this domain, we present a review and an analysis of the current work. We describe past and ongoing research of virtual reality applications for unilateral neglect and discuss the existing problems and new directions for development

Memory for complex visual objects but not for allocentric locations during the first year of life

International audienceAlthough human infants demonstrate early competence to retain visual information, memory capacities during infancy remain largelyundocumented. In three experiments, we used a Visual Paired Comparison (VPC) task to examine abilities to encode identity(Experiment 1) and spatial properties (Experiments 2a and 2b) of unfamiliar complex visual patterns during the first year of life. In the first experiment, 6- and 9-month-old infants were familiarized with visual arrays composed of four abstract patterns arranged in a square configuration. Recognition memory was evaluated by presenting infants with the familiarized array paired with a novel array composed of four new patterns. The second couple of experiments aimed to examine infant ability to encode the spatial relationships between each pattern of the array (e.g., where is A in the square configuration). The 6-, 9- and 12-month-old infants were tested on a spatial version of the VPC task, in which the novel array was composed of the same patterns than the familiarized array but arranged differently within the square configuration. Results indicated that infants retained the identity of the patterns but not their specific spatial relationships within the square configuration (i.e., allocentric location of the patterns), suggesting either an immaturity of the processes involved in object-to-location binding, or the inappropriateness of unfamiliar complex objects to reveal such early allocentric abilities