2.7. Passive avoidance test

This test began with training, in which a mouse was placed in a light chamber; when the mouse crossed over to the dark chamber, it received a mild electric shock on the foot (0.25 mA for 1 s). The initial latency to enter the dark (shock) compartment was used as the baseline measure. During the probe trials, 24 h after training, the mouse was again placed in the light compartment, and the latency to return to the dark compartment was measured as an index of passive fear avoidance. The passive avoidance test method used for cognitive behavior assessment has a 200 s maximum latency, as observed with most of the vehicle and CNO‐treated animals. Thus, it is not suited for cognitive enhancement observation, which is similar to previously published studies. 21 Future studies will need to address this issue using other methods such as novel object recognition task, Barnes maze, or Morris water maze tests. 22 , 23