Fig. 2.

Acquisition of paired-associate memory in the behavioral test. For readability, the performance index in the 3-session block, which comprised data from each animal per session for three consecutive sessions, is shown. Control, offspring born to dams that were administered corn oil; TCDD 200 and TCDD 800, offspring born to dams that were administered TCDD at an oral dose of 200 and 800 ng/kg, respectively; TBDD 200 and TBDD 800, offspring born to dams that were administered TBDD at an oral dose of 200 and 800 ng/kg, respectively. The Control group was commonly compared with the TCDD- and TBDD-exposed groups. a The performance indices of the Control and TCDD-800 groups increased with the sessions and were significantly higher than the chance value [Control, p < 0.001, F(1,14) = 14.6; TCDD-800, p < 0.001, F(1,14) = 15.1], whereas the performance index of the TCDD-200 group did not differ from the chance value [TCDD-200, p = 0.87, F(1,14) = 0.58]. The performance index of the TCDD-200 group was significantly lower than that of the Control group [p < 0.05, analysis of variance with Dunnett’s post hoc test]. b The performance index of the TBDD-exposed rat offspring showed a similar trend as that observed in TCDD-exposed rats. The performance index of the TBDD-800 group was significantly higher than the chance value [p < 0.001, F(1,14) = 4.58], whereas no significant difference was observed for the TBDD-200 group [p = 0.35, F(1,14) = 1.14]