FIGURE 1.

Dominance shows developmentally regulated experience-dependent plasticity. (A) Mice within a cage were assessed in the tube test using a round-robin design to assess dominance between each pair in a cage. (B) Timeline showing habituation to the tube and testing environment and training, followed by weekly tests of hierarchy across development. (C) Weekly changes in average David’s Score (DSs) across development (generalized linear model, p = 0.739, n = 43 mice in 11 cages) (D) DS for each rank assigned based on the average DSs across the testing period. (E) Experience-dependent changes in hierarchy for adolescent mice were assessed by altering the outcome of the rank 1 vs. 3 match-up by blocking the tube, forcing the rank 1 animals to lose. Hierarchies were reassessed 24 h later (n = 72 mice in 18 cages). (F) Timeline showing habituation to the tube and testing environment, training, three baseline tests of hierarchy every other day, followed by forced loss manipulation or natural outcome and dominance status reassessment. (G) Baseline hierarchies showed no significant differences in change in David’s Score between p29–31 and p31–33 (generalized linear model, p = 0.614, n = 72 mice from 18 cages). (H) Adolescent rank 1 mice that experienced forced loss showed significantly lower DSs compared with mice that experienced the natural outcome (Wilcoxon signed rank test, ^∗p = 0.02, n = 9 mice from 18 cages).