Fig. 1.

A social hierarchy was established in each cage of four mice. A) Schematic drawing of the experimental timeline. B) Training and testing sessions of the tube test. C) Establishment and maintenance of the social hierarchy in each cage of four mice. D) Mice were divided into dominant mice and subordinate mice according to their ranks in the tube test. E) Schematic cartoon illustrating the warm spot test. F) Duration of warm spot occupation by dominant and subordinate mice. G, H, and I) Pushing, advancing, and retreat behaviors of dominant and subordinate mice in the tube test, respectively. *p < 0.05, **p < 0.01, compared with subordinate mice, n = 20 per group.