Fig. 2: Grid cells show reduced spatial coding after PNN removal.

a, b Example grid cells from control and chABC-treated rats. Color-coded rate maps (top), running path with spikes superimposed (middle) and spatial autocorrelation maps (bottom) for four grid cells in controls (a) and four grid cells in chABC-treated rats (b). The number above the rate map is maximum firing rate and the number above the autocorrelation map is gridness score. c Removing PNNs did not reduce gridness in the familiar environment (median; Control 0.63; chABC 0.56, p = 0.694). d The dispersed spiking outside grid cell fields caused the spatial specificity of grid cells to decrease (median; Control 0.57; chABC 0.45, p < 0.0001), in addition to reducing the e spatial information (median; Control 0.36; chABC 0.2, p < 0.0001). f Maximum firing rate was reduced (median; Control 9.32; chABC 6.93, p = 0.009). g Grid cell bursting ratio was measured as the number of bursting events divided by the number of single-spike events. Rats with disrupted PNNs showed a large reduction in bursting event ratio (median; Control 0.08; chABC 0.02, p < 0.0001). h Spiking variability was measured as the coefficient of variation (CV) of interspike intervals (ISI). The method used here calculates CV of ISI using only spikes from passes though grid fields (Supplementary Fig. 5) (median; Control 0.99; chABC 0.82, p < 0.001). Violin plots show min to max and median (black line). Width of graph corresponds to number of samples for each value. Control n = 86, chABC n = 63. Mann–Whitney U test (two sided). **p < 0.01, ***p < 0.001, ****p < 0.0001. Source data are provided as a Source Data file.