They found that the grid cells closer to the changing walls ... identify the animal's location on the basis of the distorted grid patterns: "We wanted to see if the rest of the brain could still ...

This rotational offset is invariably accompanied by an elliptic distortion of the grid pattern. Reversing the ellipticity analytically by a shearing transformation removes the angular offset.

The screens that are not as bright also exhibit a grid pattern on the background -- not a set of vertical lines on the setting screen, which is normal, but a checkered pattern of horizontal and ...