Figure 4. Learning and memory ability based on the Morris water maze test.

(A) Escape latency to find the platform from days 2 to 7 of testing. Compared to controls, the bilirubin-treated rats showed a longer latency to escape onto the platform on days 5 to 7 (navigation trial). (B) The number of times the rats crossed over the platform location on day 8 (probe trial). The number of times that the bilirubin-treated rats crossed over the platform location was significantly lower when compared with that of the controls. (C) The percentage of time spent in the safety quadrant during the probe trial. Compared to controls, the bilirubin-treated rats spent less time in the platform safety quadrant. (D) Representative swimming paths. (a), (c): during the navigation trial on day 7. (b), (d): during the probe trial. Data are expressed as the mean ± SD (n = 12 in each group). *: P<0.01 vs control group; #: P<0.05 vs control group.