Wet and Dry Elevated Zero Maze

The WAZM is a transformation of the elevated zero maze (EZM) to an integrated wet and dry context. This novel apparatus is constructed from an annular platform (90 cm diameter; 10 cm width), made out of black plywood, joined to a plastic tank (70 cm diameter, 55 cm deep) elevating it 55 cm above the ground. The annular platform has two opposite, enclosed quadrants (with walls 35 cm height) and two open quadrants (with borders 5 mm height). The plastic tank that holds this platform is filled up with water (22 ± 2°C, 50 cm deep), arising to 10 cm below the platform level. Thus, the annular platform and the plastic tank comprise one unified arena (Figure 1). For the tests, rats were first habituated to the room for 4 min and then were placed into one of the open quadrants facing a closed part of the apparatus. Rats were allowed to explore the arena for a 5 mins session. During this time rats behavior was tracked, recorded and analyzed by the Etho-Vision system (Noldus Information Technology, Wageningen, Netherlands). Behavioral measures that were analyzed include the time spent in the open quadrants, distance traveled in the open quadrants, distance traveled in the closed quadrants and total freezing behavior.