TY - JOUR T1 - Grid cell firing fields in a volumetric space JF - bioRxiv DO - 10.1101/2020.12.06.413542 SP - 2020.12.06.413542 AU - Roddy M. Grieves AU - Selim Jedidi-Ayoub AU - Karyna Mishchanchuk AU - Anyi Liu AU - Sophie Renaudineau AU - Éléonore Duvelle AU - Kate J. Jeffery Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/12/07/2020.12.06.413542.abstract N2 - We investigated how entorhinal grid cells represent volumetric (three-dimensional) space. On a flat surface, grid cell firing fields are circular and arranged in a close-packed hexagonal array. In three dimensions, theoretical and computational work suggests that the most efficient configuration would be a regular close packing of spherical fields. We report that in rats exploring a cubic lattice, grid cells were spatially stable and maintained normal directional modulation, theta modulation and spike dynamics. However, while the majority of grid fields were spherical, they were irregularly arranged, even when only fields abutting the lower surface (equivalent to the floor) were considered. Thus, grid organization is shaped by the environment’s movement affordances, and may not need to be regular to support spatial computations.One Sentence Summary In rats exploring a volumetric space, grid cells are spatially modulated but their firing fields are irregularly arranged.Competing Interest StatementThe Authors declare the following competing interests: K.J. is a non-shareholding director of Axona Ltd. ER -