The amygdala, the brain nucleus responsible for the onset of sexual salience, is also responsible for potentiation of emotions of fear, aggression, violence.
The amygdala communicates with the hypothalamus proper, because sexual arousal and motivational salience is a complex process. There have to be threshold potentials in the Anterior hypothalamic nucleus for thermoregulation, sweating, shorter breathing, the Paraventricular nucleus & Supraoptic nucleus for oxytocin and vasopressin release (depending on the gender), Pituitary gland main/posterior for oxytocin, vasopressin, gonadotropes, lactotropes release, and even the Tuberomammillary and Posterior nucleus for pupil dilation, alertness, increase of ATP production. To name a few notable regions.
The amygdala also communicates with the nucleus accumbens of the reward system via the D1 motivational salience dopaminergic system, to facilitate gratification anticipation, and the 5-HT system for contentedness and reward.
The amygdala also communicates with the somatosensory system of the parietal lobe to initiate sympathetic, autonomous, and parasympathetic processes that facilitate proceptive and receptive mating behaviors.
The amygdala also communicates with the orbitofrontal cortex to inhibit lateral decision-making, compartmentalization, and risk-aversive behaviors.
Women, due to neuroanatomy and neurochemistry, can experience dissonance and due to the effects of neural facilitation, conflate sexual arousal and salience with the emotions of helplessness, threat, loss of control, aversive salience(D2 system) to being subjected to violence, et cetera.
There is some preliminary work being done on supposed selection pressures for the trait, predisposition, and manifestation, but there is a lot of stigma, unsurprisingly. The zeitgeist is that women experience rape fantasies because it frees them from the patriarchal/misogynistic stigma with regard to female sexuality, and also rids them of the agency of having sexual thoughts and an active sexuality. It's flimsy and isn't rooted in neuroscience, but it is inoffensive.
One lazy argument is that the women that were able to cope and internalize being raped, were more successful in replicating their genes, which eventually morphed into strong genetic associations through hundreds of generations. The women that were aversive to the point of resisting and fighting their aggressors, tended to suffer injury, get murdered,
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