The same rats (N = 32) tested in the open field were retested 3 days later in the elevated plus maze on postnatal day 73. Rats were placed in the central platform of the test apparatus and video-recorded for 5 min in a dimly lit (15 lux), sound-attenuated (60 dB) environment, as previously described (Pellow et al., 1985). The maze was made of Plexiglas (gray floor, black walls) and included two open (50 × 10 cm) and two closed arms (50 × 10 × 40 cm) extending from a central platform (10 × 10 cm). The apparatus was elevated 60 cm above the floor. Behavioral measures included the time spent in open and closed arms and frequency of head dips and stretched-attend postures, as described by Griebel et al., (2002).
