Grid maps are disrupted after large-scale arena expansion and recover with experience

The hexagonal firing pattern of grid cells in the medial entorhinal cortex (MEC) is thought to provide a universal spatial metric supporting vector-based navigation regardless of an environment's spatial scale. However, how the hexagonal pattern adapts to large changes in the spatial scale of an environment remains elusive. Using single-unit recordings in freely behaving male mice, we show that grid maps are substantially disrupted after large-scale but not medium-scale expansion of the recording arena. The disruption occurs when the scale ratio exceeds the scale ratio of successive grid cell modules, indicating that adaptation of grid cell representations within a module is constrained by a preconfigured spatial scale range of the module. Importantly, grid patterns recover gradually over multiple days of experience in the large-scale expanded arena. These findings challenge the notion of a universal spatial metric by grid cells, instead revealing a flexible system shaped by experience.