OPTIVISION

The peripersonal space is a limited space around the body, that plays a major role in ecological situations that require particular postural behaviors in order for example to avoid objects or predators located near and in front of the body or simply to grasp an object of interest. These apparent trivial but vital reactions require complex cerebral processing involving the integration of different sensory modalities. In this project, we propose to test the hypothesis that the location of objects in surrounding space plays a major role in the way they are processed by the visual system, and that objects located in behaviourally relevant portions of space receive a privileged visual processing. We will explore the relevance of these particular regions of space through different sensory channels: peripheral vision, muscular eye-head proprioception and vestibular modality in both static (posture) and dynamic spatial contexts (navigation). More specifically, we will study how eye and head position (gaze) signals can lead to a privileged visual processing of the straight-ahead direction, i.e. the region of space faced by the observer’s body. When the gaze is straight-ahead, the objects are processed optimally in central vision. However, when eye and/or head movements bring the gaze toward eccentric locations, the same objects are given a sub-optimal processing in peripheral vision. However, on the basis of neurophysiological data, we make the prediction that peripheral retinal information in that case is processed in a privileged way. We also make the hypothesis that a similar privileged processing is involved for objects located in the near space compared to object located further away. This particular close region can be only defined by a combination of visual information (in this case, retinal disparity) with eye position signals (in this case, vergence). We will approach this topic of posture and navigation in the near and front space by combining powerful and complementary methodologies: psychophysics, visual evoked potential in humans, fMRI in both human and non human primates and extracellular recordings in non human primates. With such multi-disciplinary approaches, it will be possible to reveal and compare the cortical networks involved in the surrounding spatial processing in both primate species and to reach a better understanding of the neuronal computations taking place in these neuronal networks. The purpose and originality of this project is not only to better understand spatial localisation through the integration of multiple visual and non-visual cues but mainly how such integration leads to an optimized distribution of resources for the visual processing of relevant regions in surrounding space to manage particular ecological situations.