Neural systems that facilitate the representation of social rank

Abstract

Across species, animals organize into social dominance hierarchies that serve to decrease aggression and facilitate survival of the group. Neuroscientists have adopted several model organisms to study dominance hierarchies in the laboratory setting, including fish, reptiles, rodents and primates. We review recent literature across species that sheds light onto how the brain represents social rank to guide socially appropriate behaviour within a dominance hierarchy. First, we discuss how the brain responds to social status signals. Then, we discuss social approach and avoidance learning mechanisms that we propose could drive rank-appropriate behaviour. Lastly, we discuss how the brain represents memories of individuals (social memory) and how this may support the maintenance of unique individual relationships within a social group. This article is part of the theme issue 'The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies'.

Keywords: animal models; neural circuits; social learning; social rank.

Figure 1.

Common species used to study social dominance in the laboratory. Fish, lizards, rodents and primates have been used to study the neural basis of dominant and subordinate behaviour in the laboratory setting. On the left, the life stage and sex in which hierarchies have been documented are listed. On the right, how dominance is assessed in the laboratory conditions is noted. Figure art by Amy Cao.

Figure 2.

Brain systems involved in the representation of a dominance hierarchy. Brain regions downstream of primary sensory processing regions (e.g. olfactory regions) involved in representing social rank are colour coded by whether local activity has been shown to represent status signals, social rank of familiar conspecifics, and social identity, as well as any combination of those types of conspecific stimuli in primates (top) and rodents (bottom). Hippocampal subregions in the rodent brain and their input and output locations are displayed in the blow-out diagram. Grey lines represent anatomical connectivity across regions. CA1, cornu ammonis 1; CA2, cornu ammonis 2; CA3, cornu ammonis 3; DG, dentate gyrus; DLPFC, dorsolateral prefrontal cortex; mPFC, medial prefrontal cortex; OFC, orbitofrontal cortex; Amyg, amygdala; STC, superior temporal cortex; HPC, hippocampus; NAcc, nucleus accumbens; VTA, ventral tegmental area; BNST, bed nuclei terminalis; BLA, basolateral amygdala; MeA, medial amygdala; PVN paraventricular hypothalamus; SUB, subiculum; VMH, ventromedial hypothalamus; PMv, ventral premammillary nucleus.