Publications by authors named "Nicolas Lebar"

Prior to goal-directed actions, somatosensory target positions can be localized using either an exteroceptive or an interoceptive body representation. The goal of the present study was to investigate if the body representation selected to plan reaches to somatosensory targets is influenced by the sensory modality of the cue indicating the target's location. In the first experiment, participants reached to somatosensory targets prompted by either an auditory or a vibrotactile cue.

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Previous studies have revealed that visual and somatosensory information is processed as a function of its relevance during movement execution. We thus performed spectral decompositions of ongoing neural activities within the somatosensory and visual areas while human participants performed a complex visuomotor task. In this task, participants followed the outline of irregular polygons with a pen-controlled cursor.

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It is well known that kinesthetic illusions can be induced by stimulation of several sensory systems (proprioception, touch, vision…). In this study we investigated the cerebral network underlying a kinesthetic illusion induced by visual stimulation by using functional magnetic resonance imaging (fMRI) in humans. Participants were instructed to keep their hand still while watching the video of their own moving hand (Self Hand) or that of someone else's moving hand (Other Hand).

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Vision is a powerful source of information for controlling movements, especially fine actions produced by the hand that require a great deal of accuracy. However, the neural processes that enable vision to enhance movement accuracy are not well understood. In the present study, we tested the hypothesis that the cortical sensitivity to visual inputs increases during a spatially-constrained hand movement compared to a situation where visual information is irrelevant to the task.

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Behavioral studies have suggested that the brain uses a visual estimate of the hand to plan reaching movements toward visual targets and somatosensory inputs in the case of somatosensory targets. However, neural correlates for distinct coding of the hand according to the sensory modality of the target have not yet been identified. Here we tested the twofold hypothesis that the somatosensory input from the reaching hand is facilitated and inhibited, respectively, when planning movements toward somatosensory (unseen fingers) or visual targets.

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