Figure 2.

Example color-coded firing rate maps in each experimental condition for a pair of simultaneously recorded place cells. The firing rate in yellow pixels was exactly zero over the entire recording session. Firing rates for the median pixel in the other color categories are shown in the key below each map; additional details of the color code are given in methods. In these maps, the firing field has been isolated by setting to zero the rate in any out-of-field pixels in which one or more action potentials occurred. By inspection of these maps, it is clear that the firing field of both cells was not disrupted in a major way by any of the manipulations. This stability held for all except one cell in a single standard session and forms the background of our analysis of the way in which card manipulations affected firing fields.