(a,b) Spatial and temporal layout of the task. During the ITI rats were waiting between two transparent barriers (rectangles). Speaker symbolizes sound cue, 1 s before image onset. Reward sites in side arms are indicated by white disks. Initial segments of both arms contain sandpaper (red) until PNR (blue bar). (c,d) During single, correct left and right trials, a subset of PRH cells (black; 1–5) showed sustained firing-rate increments or decrements during locomotion selectively in one of the side arms. For instance, PRH cell 3 shows a high tonic firing rate except for a sustained decrement selectively in the left arm. Coloured circles represent successive positions (orange: left trial with lightest colours in middle lane representing period before onset of visual cue; dark orange represents return to middle lane; purple: idem but for right trial). In contrast, hippocampal (green; 1–4) and S1BF cells (blue; 1–4) showed transient or no changes when travelling across the left or right arm. For instance, although S1BF cells 3 and 4 were tonically active, they showed a sustained decrement neither in the left nor right arm. (e) Two PRH cells (PRH unit 4 and 5; same cells as in c) showed left–right selectivity in firing rate (colour-coded) along the maze trajectories. (f) Same as (e), but now showing a hippocampal place field (CA1 unit 2; same cell as in d).