Introducing the brain: centers for sex and social drives (Introduction)

by David Turell , Friday, October 27, 2023, 17:13 (183 days ago) @ David Turell

Areas in the hypothalamus:

https://www.science.org/doi/10.1126/science.adh8489?utm_source=sfmc&utm_medium=emai...

"Abstract
Sexual, parental, and aggressive behaviors are central to the reproductive success of individuals and species survival and thus are supported by hardwired neural circuits. The reproductive behavior control column (RBCC), which comprises the medial preoptic nucleus (MPN), the ventrolateral part of the ventromedial hypothalamus (VMHvl), and the ventral premammillary nucleus (PMv), is essential for all social behaviors. The RBCC integrates diverse hormonal and metabolic cues and adjusts an animal’s physical activity, hence the chance of social encounters. The RBCC further engages the mesolimbic dopamine system to maintain social interest and reinforces cues and actions that are time-locked with social behaviors. We propose that the RBCC and brainstem form a dual-control system for generating moment-to-moment social actions. This Review summarizes recent progress regarding the identities of RBCC cells and their pathways that drive different aspects of social behaviors."

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"The RBCC orchestrates all innate social behaviors that subserve reproduction. The MPOA drives male sexual, paternal, and maternal behaviors, whereas the VMHvl and PMv promote female sexual behavior and aggression in both sexes. The MPOA and the VMHvl and PMv may have an antagonistic relationship, as indicated by their opposing roles in multiple social behaviors. At the baseline, the RBCC adjusts an animal’s physical activity, hence the chance of social encounters, on the basis of hormonal and metabolic signals. Upon encountering a social target, the RBCC engages the dopamine system to sustain the social interest and reinforce the actions and contexts that lead to the successful completion of social behaviors. The PAG has emerged as a critical midbrain relay for executing VMHvl-driven social behaviors, but the midbrain region that transforms MPOA signals into motor actions remains elusive. Regardless of the exact circuit, we propose a hypothalamic and brainstem–spinal cord dual-control system for the motor execution of each social action. In this model, medial hypothalamus activity determines the broad behavior category based on the animal’s internal state and opponent’s social identity and opens the gates to allow specific brainstem–spinal cord circuits to respond to the immediate sensory cues and drive moment-to-moment motor output. Though not discussed here, the RBCC also drives a suite of autonomic responses to prepare the body for social actions and triggers neuropeptide and hormone releases that are essential for reproduction after mating (102). Lastly, it is worth mentioning that although the RBCC circuit is hardwired developmentally, it remains plastic. The input-output relationship of the circuit can be shaped through experience during development and adulthood, enabling widely different tendencies in the expression social behaviors across individuals."

Comment: The hypothalamus is a large structure on the underside of the brain. To stimulate an act it receives visual, mental and physical stimuli. Viewed as a necessary purposeful development all of the disparate parts of the mechanism must be viewed as irreducible complex. Stepwise would not achieve the goal because the function of each part separately would not achieve a useful partial goal to be maintained until it is all put together. Design required