Title: "Self-identification modulates grid-cell like representation during virtual navigation in humans" 

Abstract: The discovery of grid cells encoding allocentric self-location has shed new light on the neural mechanisms of spatial representation. Intriguingly, their hexagonal grid-like field maps maintain in darkness and are persistent to landmark changes, which suggests that grid cells may take intrinsic self-motion cues as input for ‘path integration’, a mechanism to keep track of one’s location in space, by integrating egocentric bodily signals with allocentric environmental cues. While most seminal studies on grid cells were conducted in rodents using invasive electrophysiology, a non-invasive procedure based on fMRI has recently been proposed, which can detect BOLD activity reflecting activity of grid cell populations, (i.e., ”grid cell-like representation”) in humans. Here, our goal was to assess how grid cell activity reflecting self-location in relation with the other self-relevant information, especially self-identification (i.e. ‘which is my body’). Self-identification is a key component of bodily self-consciousness (BSC), which has been argued to originate from the integration of multisensory bodily signals from the body and the external environment. The experience of the ‘self’ is usually unified with one’s physical body. However, modern virtual reality technologies combined with online multisensory stimulation allows manipulating self-identification and detach the sense of self from the physical body, where self-identification becomes crucial to recognize oneself in space-location. Notably, recent studies have shown that illusory changes in self-identification not only alters experienced self-location, but also affects self-related spatial cognitive processes, such as spatial semantic distances and size perception. Based on these data, we hypothesized that illusory changes of BSC may affect the integration of egocentric and allocentric cues used to navigate and, thereby, grid cells activity. We assessed the impact of BSC on grid-cell like representation by systematically manipulating self-identification while participants navigated and performed a spatial memory task in a 3D virtual arena. We compared grid-cell like activity and behavioural navigation performance in the presence or absence of a self-identified avatar embedded in the virtual scene. We found that the presence of a self-identified virtual avatar disrupted grid-cell like representation patterns classically found in the entorhinal cortex. Conjointly, we found evidence for increased egocentric processing in the posterior parietal cortex. Taken together, our results indicate that bodily self-consciousness modulates the balance between allocentric grid-like computations and egocentric bodily processing during virtual navigation.