Figure 3. LTS cannot be induced by partial training when PSI occurs during the original (5X) sensitization training.
(A) Experimental protocols. The times at which the pretests, training, posttests, and drug/vehicle injections occurred are shown relative to the end of the last training session. The red arrow indicates when either anisomycin or vehicle was injected into the hemocoel. (B) The mean duration of the SWR measured at 24 h and 48 h for the Veh-Control-3XTrained (n = 5), Veh-5XTrained (n = 8), Aniso-5XTrained (n = 6), and Aniso-5XTrained-3XTrained (n = 6) groups. A repeated-measures ANOVA showed a significant group x time interaction (F[6,42] = 40.9, p < 0.0001). Planned comparisons indicated that the group differences were highly significant for both 24-h (F[3,21] = 43.9, p < 0.0001) and 48-h (F[3,21] = 45.4, p < 0.0001) posttests. SNK posthoc tests revealed that the 5X training produced sensitization of the SWR in the Veh-5XTrained group (mean duration = 50.1 ± 5.6 s) at 24 h compared with the results for the Veh-Control-3XTrained group (mean duration of the SWR = 1.4 ± 0.4 s, p < 0.001). In addition, the SWR in the Veh-5XTrained group was significantly longer than that in the Aniso-5XTrained group (2.2 ± 1.2 s, p < 0.001) and the Aniso-5XTrained-3XTrained group (4.0 ± 2.3 s, p < 0.001). The differences among the Veh-Control-3XTrained, Aniso-5XTrained, and Aniso-5XTrained-3XTrained groups were not significant at 24 h. The SWR in the Veh-5XTrained group (mean duration = 49.8 ± 5.8 s) remained sensitized at 48 h, as indicated by the comparison with the reflex in the Veh-Control-3XTrained group (mean duration = 1.2 ± 0.2 s). The SWR was also significantly prolonged in the Veh-5XTrained group compared with that in the Aniso-5XTrained group (mean duration = 2.0 ± 1.0 s, p < 0.001 for both comparisons). The three tail shocks applied after the 24-h posttest did not establish LTS in the Aniso-5XTrained-3XTrained group. The mean duration of the SWR in this group at 48 h was 2.2 ± 1.2 s, which was not significantly different from that in the Veh-Control-3XTrained and Aniso-5XTrained groups. The SWR of the Veh-5XTrained group at 48 h was significantly longer than that in the Aniso-5XTrained-3XTrained group (p < 0.001). Asterisks, comparisons of the Veh-5XTrained group with the Veh-Control-3XTrained group, the Aniso-5XTrained group, and the Aniso-5XTrained-3XTrained group.