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International audience; Background: The aim of this pilot study is to investigate the impact of virtual reality exposure therapy (VRET) on brain metabolism and connectivity. Eighteen patients with acrophobia were assessed by an F-18-FDG PET scan sensitized by virtual exposure before treatment, and nine of them were assessed again after eight sessions of VRET. Statistical Parametric Mapping was used to study the correlations between metabolism and pretherapeutic clinical scores and to compare metabolism before and after VRET (p voxel < 0.005, corrected for cluster volume). Metabolic connectivity was evaluated through interregional correlation analysis. Results: Before therapy, a positive correlation was found between scores on the behavioural avoidance test and left occipital metabolism (BA17-18). After VRET, patients presented increased metabolism in the left frontal superior gyri and the left precentral gyrus, which showed increased metabolic connectivity with bilateral occipital areas (BA17-18-19), concomitant with clinical recovery. Conclusions: This study highlights the exciting opportunity to use brain PET imaging to investigate metabolism during virtual exposure and reports the involvement of the visual-motor control system in the treatment of acrophobia by VRET.

International audience; Much is known about how different spatial reference frames continually interact to support spatial navigation, but less explored is whether it is more crucial to process object-to-object information or egocentric heading information for effective orientation in a cluttered environment. To address this question, we evaluated the possible influence on spatial performance of an interactive aerial view of different scale (small vs. large) comprising an arrow indicating participants' egocentric heading. Results revealed that the presence of a small interactive aerial view including a visualized larger arrow facilitated the retrieval of stored spatial layout. These data are consistent with recent studies revealing the role of retrosplenial cortex in translating between different spatial reference frames, and may contribute to elucidate the continuous synchronization between the inter-object direction information in the environment with respect to egocentric current heading. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

International audience; Designing multimodal virtual environments promises revolutionary advances in interacting with computers in the near future. In this paper, we report the results of an experimental investigation on the possible use of surround-sound systems to support visualization, taking advantage of increased knowledge about how spatial perception and attention work in the human brain. We designed two auditory-visual cross-modal experiments, where noise bursts and light-blobs were presented synchronously, but with spatial offsets. We presented sounds in two ways: using free field sounds and using a stereo speaker set. Participants were asked to localize the direction of sound sources. In the first experiment visual stimuli were displaced vertically relative to the sounds, in the second experiment we used horizontal offsets. We found that, in both experiments, sounds were mislocalized in the direction of the visual stimuli in each condition (ventriloquism effect), but this effect was stronger when visual stimuli were displaced vertically, as compared to horizontally. Moreover we found that the ventriloquism effect is strongest for centrally presented sounds. The analyses revealed a variation between different sound presentation modes. We explain our results from the viewpoint of multimodal interface design. These findings draw attention to the importance of cognitive features of multimodal perception in the design of virtual environment setups and may help to open new ways to more realistic surround based multimodal virtual reality simulations.

Virtual Reality prototyping can be used early in a design process, in order to question observers about the aesthetics of future vehicles, without the need for physical mock-ups. However, it is suspected that numerical display formats and solutions are not all equivalent, concerning the physical dimensions an observer is able to appreciate. This question is particularly acute, if one considers the transferability of conclusions reached using virtual prototyping to the real outcome of the design process.

International audience; Numerous studies highlighted the influence of a tilted visual frame on the perception of the visual vertical ('rod-and-frame effect' or RFE). Here, we investigated whether this influence can be modified in a virtual immersive environment (CAVE-like) by the structure of the visual scene and by the adjustment mode allowing visual or visuo-kinaesthetic control (V and VK mode, respectively). The way this influence might dynamically evolve throughout the adjustment was also investigated in two groups of subjects with the head unrestrained or restrained upright. RFE observed in the immersive environment was qualitatively comparable to that obtained in a real display (portable rod-and-frame test; Oltman 1968, Perceptual and Motor Skills 26 503-506). Moreover, RFE in the immersive environment appeared significantly influenced by the structure of the visual scene and by the adjustment mode: the more geometrical and meaningful 3-D features the visual scene contained, the greater the RFE. The RFE was also greater when the subjective vertical was assessed under visual control only, as compared to visuo-kinaesthetic control. Furthermore, the results showed a significant RFE increase throughout the adjustment, indicating that the influence of the visual scene upon subjective vertical might dynamically evolve over time. The latter effect was more pronounced for structured visual scenes and under visuo-kinaesthetic control. On the other hand, no difference was observed between the two groups of subjects having the head restrained or unrestrained. These results are discussed in terms of dynamic combination between coexisting reference frames for spatial orientation.