Changes in spatial self-consciousness elicit grid cell-like representation in the entorhinal cortex.
Hyuk-june Moon, Louis Albert, Emanuela De Falco, Corentin Tasu, Baptiste Gauthier, Hyeong-dong Park, Olaf Blanke
Proceedings of the National Academy of Sciences of the United States of America March 19, 2024 DOI: 10.1073/pnas.2315758121
Summary
Illusory changes in self-location can activate grid cell-like representations in the entorhinal cortex, similar to traditional navigation. In a study involving 30 participants, visuo-tactile bodily stimuli induced perceived shifts in location without visual cues, revealing that these perceptual shifts correlate with grid cell activity. The strength of this response was directly linked to the magnitude of the perceived self-location change, showcasing that both environmental navigation and multisensory bodily cues engage the same neural mechanisms for spatial awareness.
Abstract
Grid cells in the entorhinal cortex (EC) encode an individual's location in space, integrating both environmental and multisensory bodily cues. Notably, body-derived signals are also primary signals for the sense of self. While studies have demonstrated that continuous application of visuo-tactile bodily stimuli can induce perceptual shifts in self-location, it remains unexplored whether these illusory changes suffice to trigger grid cell-like representation (GCLR) within the EC, and how this compares to GCLR during conventional virtual navigation. To address this, we systematically induced illusory drifts in self-location toward controlled directions using visuo-tactile bodily stimulation, while maintaining the subjects' visual viewpoint fixed (absent conventional virtual navigation). Subsequently, we evaluated the corresponding GCLR in the EC through functional MRI analysis. Our results reveal that illusory changes in perceived self-location (independent of changes in environmental navigation cues) can indeed evoke entorhinal GCLR, correlating in strength with the magnitude of perceived self-location, and characterized by similar grid orientation as during conventional virtual navigation in the same virtual room. These data demonstrate that the same grid-like representation is recruited when navigating based on environmental, mainly visual cues, or when experiencing illusory forward drifts in self-location, driven by perceptual multisensory bodily cues.