FIGURE 14-12 Classes of Spatially Related Cells in the Hippocampal Formation At right in each part, X–Y coordinates indicate the directional selectivity of the cell recorded at left. (A and B) Place cells discharge when a rat is at a spatial location, irrespective of its orientation. (C) Head direction cells discharge when the rat’s head points in a given direction, irrespective of its location. (D) Grid cells discharge at many locations, forming a virtual grid that is invariant in the face of changes in the rat’s direction, movement, or speed.

Research from O’Keefe, 2006, Fig. 11-21.
Courtesy of John O’Keefe.