Although male heterosexual studies have dominated the literature, broadly speaking, active brain areas during sexual arousal are highly similar for both men and women of all sexual orientations. Studies comparing sexual arousal in the brains of men and women generally note that women have weaker responses to the visually erotic stimuli that are common of sexual neuroimaging studies.

However, relatively few studies have compared male and female participants and although discrete sex differences in sexual brain activation clearly exist, they have varied across studies. More thorough research will be necessary to determine which results are reliable and whether other sex differences exist.

Context is key

Some recent studies indicate that the context and format of the visual sexual stimuli commonly used in neuroimaging studies might not be enough to get the average woman as equally fired up as the average man is when presented with visually erotic stimuli – women are sexually more complex creatures. In fact, women in some studies, have been shown to have a stronger neural response than men, albeit when smelling pheromones in the sweat of sexual partners.

Recently, when comparing men and women’s responses to erotic videos that either set the mood (having an emotional component and story) or physically set the scene (where sexual intercourse and genitalia where directly displayed) women’s responses were stronger for the mood type videos, whereas the men preferred the physical type videos. Research also indicates that women have a more profound temporal component to sexual arousal than men. Although currently poorly understood, the least sexually aroused time is considered the follicular phase, a potentially fertile period, enabling females to be selective and cautious when committing to a sexual encounter in this period.

Sexual preference

Where men show a robust neural reaction in brain regions involved in visual attention, motivation, and genital arousal to erotic stimuli depicting one sex, and very little reaction in these regions to erotic stimuli depicting the other sex, women show more similar reactions to both types of erotic stimuli. In other words, both heterosexual and homosexual men have stronger activation for images of their preferred sex than their non-preferred sex. In contrast, women have more similar reactions to both sexes and do not differ between sexual orientations.

Orgasm and brain activation patterns

Similarly, and in spite of the general perception that male orgasms are from Mars and female orgasms are from Venus, men and women again have similar brain activity patterns during orgasm. It is worth nothing that although orgasm studies show similar brain activity patterns, discrete activations and deactivations vary depending on how orgasm was achieved.

In both sexes, four different nerve systems connect the genitals to the brain, which, with a stimulation surge, shoot excitatory signals to the brain upon reaching orgasm. Subsequently, regions all over the brain appear to light up, while the vmPFC and amygdala are shut down —reportedly like taking heroin. The deactivations are considered to constitute the temporary sexual disinhibition required for an orgasm to take place, ‘robbing’ us of the voice of reason that controls our behavior and critical thinking.

Neurochemical love buzz

And we can’t forget the neurochemical cocktail that results in a “cloud-nine” buzz both during and after orgasm. How men and women’s bodies react to this chemical mash, including oxytocin, prolactin and endorphins, is perhaps where the sexes differ most profoundly and is shrouded in confusion and controversy. Many functions are attributed to this neurochemical rush from bonding and cuddling behavior, to enhancing the chances of successful reproduction.

Future implications for neuroimaging and the brain on sex

Research has essentially revealed the tip of the iceberg when it comes to understanding sexual arousal in the brain. Developing and expanding on the neural model of sexual arousal should provide valuable insights into the cognitive, emotional, motivational and physiological aspects of sexual arousal. Seeing as these studies lie at the boundaries between the mental and physical, further developments will surely shed light on Freudian theories of sexual desires.

More importantly, gaining a deep understanding of the neural underpinnings of sexual arousal will ultimately contribute to solving public health problems such as sexual disorders and sexual offending. We have much to learn.

References

Chung WS, Lim SM, Yoo JH, & Yoon H (2013). Gender difference in brain activation to audio-visual sexual stimulation; do women and men experience the same level of arousal in response to the same video clip? International journal of impotence research, 25 (4), 138-42 PMID: 23303334

Stoléru S, Fonteille V, Cornélis C, Joyal C, & Moulier V (2012). Functional neuroimaging studies of sexual arousal and orgasm in healthy men and women: a review and meta-analysis. Neuroscience and biobehavioral reviews, 36 (6), 1481-509 PMID: 22465619

Sylva D, Safron A, Rosenthal AM, Reber PJ, Parrish TB, & Bailey JM (2013). Neural correlates of sexual arousal in heterosexual and homosexual women and men. Hormones and behavior, 64 (4), 673-84 PMID: 23958585

Image via Parinya / Shutterstock.