Water maze place navigation

Place navigation was assessed as described previously (Ring et al., 2007; Steubler et al., 2021). A white circular pool (150 cm diameter) contained milky water (24–26°C). Acquisition training consisted of 18 trials (6 per day, inter-trial interval 30–60 min) during which the submerged platform (14×14 cm) was left in the same position. Trials lasted a maximum of 120 s. To monitor reversal learning, the platform was moved to the opposite position for 2 additional days of testing (6 trials per day). Trials were video-tracked using a Noldus EthoVision. Raw data were transferred to the software Wintrack for analysis.³ Results were plotted in bins of 3 trials. Passive floating episodes were defined as immobility or decelerations with speed minimum <0.06 m/s and removed from the data before calculating swim speed. A slightly modified version of Whishaw’s error was calculated as path (%) outside a 18.5 cm wide corridor connecting release point and goal. Cumulative search error was determined by summing the distances to target measured at 1 s intervals and subtracting value that would be obtained for an ideal direct swim. Finally, wall-hugging was quantified by time (%) spent in a 10 cm wide wall zone. The first 30 s of the reversal trial served as probe trial to test for spatial retention.