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. Author manuscript; available in PMC: 2013 Apr 1.
Published in final edited form as: Nat Neurosci. 2012 Sep 16;15(10):1445–1453. doi: 10.1038/nn.3215

Figure 7.

Figure 7

Moment-to-moment changes of the cell's PFD in two examples of resetting trials. For each example the foraging path is shown in the left panels (a, c), and the moment-to-moment HD of the animal coupled with cell activity (black bars) (Firing rate × HD × Time) is shown in the right panels (b, d). a & c, The animal's path has been divided into three parts: the outbound path is shown in black, the return path (from the pellet to the edge of the arena) is represented in red, and the correction path (from the apparatus edge to the refuge) is shown in blue. b & d, The red dots indicate the HD and time at which the cell's firing rate reached 50% of its maximum firing rate. Successive sampling episodes were isolated and the tuning curves for each episode (red trace) are compared with a reference (black trace). b, In panel 1 the cell's PFD at the beginning of the trial is compared to the only inter-trial value that could be recorded in that session (inter-trial value 2). In panels 2 to 4 the cell's PFD is compared to the PFD recorded at the beginning of the trial, and shows a slow drift counter-clockwise while the rat forages for the food pellet. Panel 5 shows the cell's PFD while the rat is correcting its orientation after reaching the wall of the arena (a, blue path) and presumably first perceives that it made an error. At that time, the PFD is reset to the value it had at the beginning of the trip (black). Notably, the cell does not fire when the rat is facing 170° (29th sec), which suggests that it was reset before reaching the refuge. This result would suggest that when the rats correct their homing direction (from apparatus edge to refuge), the cell's PFD is reset at the same time on their way to the refuge. d, Panels 1 to 3 show the cell's PFD drifting clockwise away from the preceding inter-trial value (black curve). Importantly, panel 4 shows that however the rat is correcting its error on its return to the refuge, the cell did not reset until the rat entered the refuge (panel 5). In this example, a second cell is visible with a PFD around 260° (green dots). Notably, these two cells are shifting in register: when the animal reaches the refuge, the first cell resets (red dots) and the PFD of the second cell (green dots) shifts approximately the same amount.