Visualizing and quantifying local distortions of grid patterns.

a, b) Generated spike locations with noise on grid field locations applied only on the east side of the arena (see text for details, 2 example cells). The color of each spike location shows the score. Shown above: Ψ score. c) East-west (left) and south-north (right) partitioning of the arena. Black lines show partition boundaries. Colors of partitions indicate the Ψ score within the partition for the examples in a (top) and b (bottom). d) Ψ score in partitions along west-east axis (dark blue) and south-north axis (light blue). Crosses show results for 10 randomly generated spike maps with noise on field locations applied only on the east side. Filled circles indicate the mean over 10 realizations. e) Spike locations of two example cells recorded in a rat that explored the northern and southern half of a box. The two halves are separated by a wall (dashed gray line). The spikes in each half were recorded in separate sessions. Color-coding as in a. f) Spike locations of the two cells shown in e while the rat explored the entire arena after the separating wall was removed. g) Grid score in south-north partitions before wall removal (left) and after wall removal (right) for the cells in e, f. Color-coding as in c. h)Ψ scores in the south-north partitions shown in g for 11 recorded cells. Crosses denote individual cells, filled circles the mean across cells. Ψ scores before wall removal in dark blue, Ψ scores after wall removal in light blue. i)Ψ scores in west-east partitions for the cells in e, f. Arrangement as in g. j)Ψ scores in the west-east partitions shown in i. Same recordings and arrangement as in h. Data in panels e-j kindly provided by [19].