CFC performance of 3 month old mice on the C57BL/6J background. (a–c) Freezing (seconds) during 3 min of shock-context test (SC-t, black bars) and context-shock test (CS-t, grey bars). C, control; Tr, trisomic. F, female; M, male. Difference between CS-t and SC-t within sex and DS line: * p < 0.05–0.01; ** p < 0.01–0.001; # p < 0.001–0.0001; ## p < 0.0001; ns, not significant. Error bar represent the SEM. Number of animals in SC and CS, respectively: (a) FC, 12,11; FTr, 9,10; MC, 13,16; MTr, 10,10; (b) FC, 12,13; FTr, 13,16; MC, 11,12; MTr, 10,10; (c) FC, 11,13; FTr, 12,16; MC, 12,20; MTr, 10,19. (d–f) Freezing during CS-t 30 second intervals for the same sex and DS lines as in (a–c). Filled circles, female controls; open circles, female trisomics; filled squares, male controls; open squares, male trisomics.