Spatial coding and attractor dynamics of grid cells in the entorhinal cortex

•Spatial responses of grid cells with identical spacing are precisely matched.•Grid cell firing is modulated primarily by slowly varying synaptic inputs.•Inhibitory neurons mediate recurrent connectivity between grid cells in layer II.•These recent results support attractor models of grid cell dynamics.•Grid cell activity may represent position with exceptionally large dynamic range.

Recent experiments support the theoretical hypothesis that recurrent connectivity plays a central role within the medial entorhinal cortex, by shaping activity of large neural populations, such that their joint activity lies within a continuous attractor. This conjecture involves dynamics within each population (module) of cells that share the same grid spacing. In addition, recent theoretical works raise a hypothesis that, taken together, grid cells from all modules maintain a sophisticated representation of position with uniquely large dynamical range, when compared with other known neural codes in the brain. To maintain such a code, activity in different modules must be coupled, within the entorhinal cortex or through the hippocampus.