The social network: Neural control of sex differences in reproductive behaviors, motivation, and response to social isolation

Abstract

Social animal species present a vast repertoire of social interactions when encountering conspecifics. Reproduction-related behaviors, such as mating, parental care, and aggression, are some of the most rewarding types of social interactions and are also the most sexually dimorphic ones. This review focuses on rodent species and summarizes recent advances in neuroscience research that link sexually dimorphic reproductive behaviors to sexual dimorphism in their underlying neuronal circuits. Specifically, we present a few possible mechanisms governing sexually-dimorphic behaviors, by hypothalamic and reward-related brain regions. Sex differences in the neural response to social isolation in adulthood are also discussed, as well as future directions for comparative studies with naturally solitary species.

Sex-dependent control of pheromones on social organization within groups of wild house mice

“…These findings are well in line with previous knowledge from pairwise behavioral assays in which females engage in more social interactions and find them more rewarding. 88 , 89 , 90 , 91 Our current results extend these past findings into the context of a group and show that sex differences in social motivation, including greater sociability in females, are maintained in complex social structures under naturalistic settings. Similarly, extensive sex differences in the dynamics and behavioral strategies undertaken to form hierarchies were also found in other mammalian species, including hyenas, 87 , 92 foxes, 93 rhesus monkeys, 94 baboons, 95 , 96 and even humans.…”

A thalamo-preoptic pathway promotes social grooming in rodents

“…It is also likely to be involved in the control of instinctive behaviors in humans. 3 Social sensory inputs are known to reach the cerebral cortex via the thalamus; however, it is not known how information needed for social behavior arrives in the hypothalamus.…”

Epigenetic Mechanisms of Brain Sexual Differentiation

“…Transcriptomic and epigenomic characterization of BNST ERα-expressing neurons revealed that sexual differentiation does not constrain the capacity to mount a genomic response to estradiol in adulthood. Likewise, manipulation of hormone levels, chemosensory input, or neuronal activity causes both sexes to engage in behaviors typical of the opposite sex, once considered "sexspecific" (Wei et al 2021;Zilkha et al 2021). These findings converge upon a model of behavioral sex differences as probabilistic rather than absolute: perinatal estradiol establishes differential gating or thresholding of shared neural circuitry, providing quantitative variation in behavioral intensity as opposed to qualitative presence or absence of hard-wired behaviors.…”