Fig. 4

Memory functions in 5-HTT-deficient mice. a Correct responses (%) in the T-maze spontaneous alternation test. b–k Barnes maze test: b the number of errors to first reach the target hole, c latency to reach the target hole, d distance traveled to first reach the target hole, and e number of omissions during the acquisition session. f–k Time spent around the target hole in the probe trial 1 day (f) and 28 days (i) after the last acquisition session. In each probe trial, time spent around the target hole was compared to averaged time spent around 11 non-target holes (g, j) and averaged time spent around two holes adjacent to the target hole (h, k). l–p Contextual and cued fear conditioning test: freezing (%) in the conditioning session (l conditioned stimulus, CS, 55-dB white noise, 30 s; unconditioned stimulus, US, 0.3-mA footshock, 2 s) and in the context test (m) and cued test (n) one day after the conditioning. Freezing (%) was also measured in the context test (o) and cued test (p) 29 days after the conditioning. Values are means ± SEM. a–f, i, l–p Asterisks and daggers indicate statistically significant differences between groups (5-HTT−/− vs. 5-HTT+/+, *p < 0.05 and **p < 0.01; 5-HTT−/− vs. 5-HTT+/−, ^†p < 0.05 and ^††p < 0.01; 5-HTT+/− vs. 5-HTT+/+, ^§p < 0.05 and ^§§p < 0.01). g, h, j Asterisks represent statistical significance with paired t tests (**p < 0.01)