title: Grid-like Processing of Imagined Navigation.
abstract: Grid cells in the entorhinal cortex (EC) of rodents [1] and humans [2] fire in a hexagonally distributed spatially periodic manner. In concert with other spatial cells in the medial temporal lobe (MTL) [3-6], they provide a representation of our location within an environment [7, 8] and are specifically thought to allow the represented location to be updated by self-motion [9]. Grid-like signals have been seen throughout the autobiographical memory system [10], suggesting a much more general role in memory [11, 12]. Grid cells may allow us to move our viewpoint in imagination [13], a useful function for goal-directed navigation and planning [12, 14-16], and episodic future thinking more generally [17, 18]. We used fMRI to provide evidence for similar grid-like signals in human entorhinal cortex during both virtual navigation and imagined navigation of the same paths. We show that this signal is present in periods of active navigation and imagination, with a similar orientation in both and with the specifically 6-fold rotational symmetry characteristic of grid cell firing. We therefore provide the first evidence suggesting that grid cells are utilized during movement of viewpoint within imagery, potentially underpinning our more general ability to mentally traverse possible routes in the service of planning and episodic future thinking.
authors.affiliation: UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AZ, UK; UCL Institute of Neurology, Queen Square, London WC1 3BG, UK. Electronic address: aidan.horner@york.ac.uk.
authors.forename: Aidan J
authors.initials: AJ
authors.lastname: Horner
authors.affiliation: UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AZ, UK; UCL Institute of Neurology, Queen Square, London WC1 3BG, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: Bisby
authors.affiliation: UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AZ, UK.
authors.forename: Ewa
authors.initials: E
authors.lastname: Zotow
authors.affiliation: UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AZ, UK; UCL Institute of Neurology, Queen Square, London WC1 3BG, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bush
authors.affiliation: UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AZ, UK; UCL Institute of Neurology, Queen Square, London WC1 3BG, UK. Electronic address: n.burgess@ucl.ac.uk.
authors.forename: Neil
authors.initials: N
authors.lastname: Burgess
mesh_terms: D000328:Adult; D018728:Entorhinal Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D007092:Imagination; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D033281:Nontherapeutic Human Experimentation; D009949:Orientation / Q000502:physiology*; D013028:Space Perception