Figure 4
Paradigm of the active avoidance test in zebrafish. (A) During the 11-week feed periods, the active avoidance test was performed at 8 weeks (first test) and 9 weeks (second test). Each test comprised two adaptation periods (gray; 20 min each) and two session periods (white). In the latter half (10 min) of the first adaptation period, we measured spontaneous motor activity. (B) 3D diagram of the shuttle box (20 × 10 × 10 cm) for active avoidance test, filled with water (shown by blue line) from the recirculation system. The shuttle box was divided into two compartments of equal size by a hurdle. (C) The active avoidance test in each session contained 60 trials. Each trial comprised a 15-s interval prior to cue presentation and cue presentation in which the fish was given a cue in the form of a lit red LED lamp for 10 s followed by punishment by mild electric shock (2.5 V); the punishment was continued for 10 s, but was stopped when the zebrafish moved to the other compartment. “Avoidance” describes zebrafish that crossed hurdle without punishment. “Failure” describes zebrafish that not Avoidance.
