A multilevel circuit gating framework for transforming sexual motivation into sexual action: Insights from mouse models

Sexual behaviour consists of a appetitive phase and a consummatory phase. Based primarily on research evidence from rodents (particularly male mice), this paper presents a multi-level gate model that explains how the transition between these two phases occurs. In this model, the processing of cues associated with a potential mate is initiated in the main olfactory bulb (MOB) and the accessory olfactory bulb (AOB) systems. These cues are then transmitted through limbic circuits, such as the medial amygdala (MeA) and the bed nucleus of the stria terminalis (BNST), where they are encoded as valuable mating information. Subsequently, these cues are integrated with internal motivational states, including social cues, hormonal status, Sexual reward experience, and sexual satiety, within cell-type-specific circuits centred on the preoptic area (POA). This integration process results in the generation of a motivational gain. When intrinsic motivational states are integrated with somatosensory inputs related to the partner, a state-dependent sensory contact gating mechanism facilitates the transition from exploratory contact to mating behaviours (e.g. mounting). In the downstream process, theperiaqueductal gray (PAG), brainstem, spinal cord, and mesolimbic reward circuits coordinate the sequence of intromission and ejaculation behaviours. During the process of mating, feedback mechanisms such as reward reinforcement and sexual reward modulate future motivational states and action thresholds. Finally, we discuss sex differences in the neural mechanisms underlying the transition from appetitive to consummatory. This conceptual model provides a testable hypothesis regarding the neural mechanisms underlying sexual dysfunction caused by insufficient sexual motivation or disrupted action gating thresholds.