Neurobiology of Human Sexuality


Human sexuality is a subject that has been taboo for many centuries. The orgasm, for example, is just one aspect of sexuality that has been overlooked. In particular, the female orgasm is an important function to discuss because it’s a topic that has been socially steeped in silence and shame, and is directly connected to female health on the whole. Very few people are willing to admit, that orgasms in fact help a woman physically and psychologically in many ways (i.e. easing menstrual cramps to alleviate stress).

One mystery regarding the female orgasm is why some women “fake” orgasms during sexual activity. One thing that is for sure, is that while the male orgasm is reached quicker, the female orgasm can result in prolonged pleasure.

Why is it that numerous women have difficulty experiencing an orgasm and why do men climax so fast? Fascinatingly enough, the large majority of women will confess that their lovers do not give them orgasm. Instead, they allow themselves to have orgasms. Not just that, but they can have a variety of different types of orgasms concurrently. (i.e. clitoral orgasms, G-spot orgasms, vaginal orgasms, ejaculatory orgasms, blended orgasms, etc). Men will comment for example, that the scent of a woman is what drives them crazy during sexual activity and makes them unable to maintain the sensation for long. So do women have more control over physical pleasure in the brain than men? Just how do sexual problems happen in the brain?

There is a combination of things that come in effect when it comes to an orgasm in the brain. Neurotransmitters, and neuro-peptides for example, are greatly involved in the sexual response. To achieve an orgasm, the central nervous system transmits orders to the heart, so that it pumps faster, delivering blood to oxygenate the increase of blood flow in muscle tissues involved in sexual activity.

Nitric oxide, serotonin, dopamine, epinephrine, and norepinephrine, are just some of the neurotransmitters and neuro-peptides involved in sexual activity. Nitric oxide (NO) plays a critical role in both male and female sexuality. In penile erections, NO induces the release of guanylate cyclase, which, in turn, converts GTP to cGMP and produces relaxation of smooth muscles and increased blood flow into the penis.

This information is used in the popular drug sildenafil (ViagraTM) that inhibits the metabolism of cGMP to prolong the effects of the erection. Serotonin’s role in sexual function is that of constriction of smooth muscles in the genitals, and peripheral nerve function. Epinephrine appears to be involved in maintaining the penis in a flaccid state. This raises the rate and force of the muscle’s contractions during sexual activity.

On the other hand, in women, epinephrine has been verified to increase vaginal pulse amplitude. Norepinephrine is another neurotransmitter that mediates chemical communication in the sympathetic nervous system, a branch of the autonomic nervous system. Like other neurotransmitters, it is discharged at synaptic nerve endings to transmit the signal from a nerve cell to other cells. Levels in the brain of neropinephrine vary in accordance to sexual arousal. They escalate considerably with arousal and sexual activity in men and in women.

Hormone levels are also included in sexual activity. In males, testosterone levels remain in many instances above the threshold required for sexual interest and activity. Thus increasing testosterone above this threshold are believed to have additional effects on sexual interest or behavior. Fascinatingly, estrogen(the “female hormone”) seems to have little impact on sexual desire on either males or females. Estrogen deficient women, however, may result in decreased genital lubrication a result of the thinning of the vaginal epithelium. Each one of the factors can impair both the physiological and psychological aspects of sexual arousal.

Additional hormonal influences in sexual function include oxytocin, cortisol, pheromones, and prolactin. There is some evidence showing that oxytocin (produced by dopamine) levels increase during sexual arousal and orgasm in both men and women. Also the combination of oxytocin and female hormones like estrogen in women, encourage an emotional attachment with a lover. In men, the bonding effect is muted, as a result of the male’s higher testosterone levels.

All of these factors come into play regarding why women have a much more difficult time achieving orgasm and why men can attain it so quickly. If women could get to a place where the emotional and mental issues are working in conjunction with their hormones, then they too could achieve orgasms as quickly as men can.


by Kali DuBois