Fig. 3.

Reversal of stimulus reinforcement in the big and small conditions. The reinforcement of the stimuli was reversed each time a mouse reached criterion so that the previously correct location became the incorrect location and vice versa. (A) There was no difference between the groups in the big separation condition in the number of reversals. con, control; run, runner. (B) Runners performed better than controls in the reversal task when the separation between stimuli was small (*P < 0.002). (C) Significant correlation between task performance in the small condition and newly born neuron density was observed (P < 0.03). Confocal images of BrdU-positive cells in the dentate gyrus of sections derived from control (D) and runner (E) mice 10 weeks after the last injection. Sections were immunofluorescent double-labeled for BrdU (green) and NeuN (red). (Scale bar: 50 μm) (F) Newly born neuron density was increased in runners as compared with controls (*P < 0.0001).