On my washing machine, there is a lock. To activate it, you must hold down the start button for a particular length of time at just the right intensity; too soft and nothing happens, too hard and the machine beeps angrily at you. Once you’ve mastered the technique, it’s easy; the lights switch on, things start moving and the cycle ultimately climaxes in a shuddering whirling crescendo of noise. Finally, an entangled heap of damp but refreshed clothes tumbles out at the other end. But for the uninitiated, it’s a perplexing mystery.  Consider now the female orgasm. JD Salinger once wrote that “a woman’s body is like a violin; it takes a terrific musician to play it right”. Pressed or caressed the right way, a woman can be transported to such ecstasy, that for a few seconds, the rest of the world ceases to exist. But get it wrong and pain, frustration, or dull nothingness can ensue. It’s a stark contrast to a man’s experience; so long as they can get an erection, a few minutes of vigorous stimulation generally results in ejaculation.  Why are orgasms so intensely pleasurable? How come women can experience multiple orgasms? And does the fabled G-spot even exist? These are some of the most enduring mysteries of medicine. “We are able to go to the moon, but we do not understand enough about our own bodies,” says Emmanuele Jannini at the University of Rome Tor Vergata – one of those who has spent his career trying to unravel it. Recent years have seen a flurry of studies by these real-life Masters of Sex, and they are finally getting some answers.  Perhaps the scientists’ greatest skill is in persuading women to sweep aside their inhibitions, and masturbate – or even copulate – under the full glare of scientific research, including the uncomfortable environment of the fMRI scanner. One of the leaders of this research has been Barry Komisaruk at Rutgers University in New Jersey, who wanted to probe whether brain differences can explain why women and men experience sex so differently.  What we see is an overall activation of the brain – it’s all systems go  It turns out that despite their varied experiences, both men and women show roughly the same neural activity during orgasm. “The similarities between men and women at orgasm are far greater than the differences,” says Komisaruk. “What we see is an overall activation of the brain; basically it’s like all systems go.”  This may explain why orgasms are so all-consuming – if the whole forest is blazing, it’s difficult to discriminate between the different campfires that were there at the start. “At orgasm, if everything gets activated simultaneously, this can obliterate the fine discrimination between activities,” Komisaruk adds. It is maybe why you can’t think about anything else.  There are hotspots in this furnace, however. One is the nucleus accumbens, a brain region that deals in pleasure and reward through the release of a neurotransmitter called dopamine. Given the choice, rats will choose electrical stimulation of this brain region over food - to the extent that they would allow themselves to starve to death. Besides sex, it’s also activated by cocaine, amphetamine, caffeine, nicotine and chocolate. No wonder orgasms make you want to keep on going back for more.  After orgasm, however, some important differences do emerge, which might begin to explain why men and women react so differently after climax. Komisaruk, with Kachina Allen, has found preliminary evidence that specific regions of the male brain become unresponsive to further sensory stimulation of the genitals in the immediate aftermath of orgasm, whereas women’s brains continue to be activated: this may be why some women experience multiple orgasms, and men do not.  If these brain scans have generated some controversy, it has been nothing compared to the attempts to pin down the anatomy of the orgasm. The penis has just one route for carrying sensations to the brain, the female genital tract has three or four. At the seat of female sexuality is the clitoris: familiar to most as a small, pebble-shaped nubbin, plonked in an awkward position, a centimetre or so in front of the vaginal opening. Precisely who discovered the importance of this structure is up for debate. Ice-age clay models, known as “Venus figurines”, depict a faceless woman with large breasts, a rounded belly, a prominent vagina and labia – and on one model, a clitoris.  It wasn’t until the 16th Century that the clitoris began to be described as a distinct physical structure, common to all women, with the function of inducing pleasure. In his book, De re anatomica, published in 1559, Realdo Columbo described the clitoris as “the seat of a woman’s delight”. Yet in subsequent centuries, female pleasure took a back seat, and the clitoris was largely forgotten – at least by anatomists and physicians. It re-emerged in the 20th Century, but was still regarded as inferior by many. Though Sigmund Freud at least acknowledged that women can experience orgasm, he believed that clitoral responsivity is superseded by vaginal orgasm in mature women. The inability to experience vaginal orgasms is associated with psychosexual immaturity, he wrote.  If that were true, then there would be an awful lot of women out there who just aren’t realising their sexual potential. Between thirty and forty percent of women claim never to have experienced an orgasm through vaginal penetration alone – though many more can orgasm through clitoral stimulation.  The suggestion that the vaginal orgasm is somehow superior has irked many feminists. It sounds as if women who don’t experience vaginal orgasms just aren’t trying hard enough. So should vaginal orgasms be a rite of passage for all women, or just a privileged few? Is it even possible to have an orgasm in the absence of a clitoris?  As soon as I touched the cervix, the rats would become rigidly immobile – Barry Komisaruk  Barry Komisaruk took the first steps to answering these questions by chance, while he was studying mating behaviours in rats. One day, while inserting a rod into a female rat’s vagina, he triggered a bizarre response: “As soon as I touched the cervix, the rats would become rigidly immobile,” he says. Not only that, but during this kind of stimulation, the rats became apparently insensitive to pain. Soon afterwards, he switched his rats for women, and noticed the same thing: vaginal stimulation blocked the transmission of pain. But how?  To find out, Komisaruk conducted a study with Beverly Whipple that looked at women with varying degrees of spinal cord injury. They found that even when their injuries blocked the known nerve pathways in the spinal cord from the genitals to the brain, these women could still feel when their vagina and cervix were being touched. Some even experienced orgasm from it, despite the pudendal nerve – which carries sensations from the clitoris to the brain – being cut. “Women with spinal cord injury who could not feel their clitoris, nevertheless had orgasms from vaginal stimulation,” says Komisaruk. “That’s probably the best evidence that vaginal orgasms exist.”  The reason is that from the vagus nerves, which are situated outside the spinal cord, carry sensations from the vagina to the brain. “Women describe clitoral orgasms as more localised and external, and vaginal orgasms as being internal and involving the whole-body; that’s probably because the nerves that carry sensations from the clitoris are different from the nerves from the vagina,” Komisaruk adds. And as for the puzzling fact that vaginal orgasms can block pain, the nerves connected to the spinal cord may inhibit the release of the neurotransmitter involved in pain perception. Once signals reach the brain, they could also trigger the release of neurotransmitters like endorphins that also relieve pain.  So if different nerves can carry sensations from different regions of the female genitalia – and both can trigger orgasm – are some regions of the vagina more sensitive than others? Where should couples go hunting for the elusive vaginal orgasm?  The famed “G-spot” was, for a long time, the prime target. The term was first coined in the early 80s, for the German obstetrician and gynaecologist, Ernst Gräfenberg. In 1950, he described an erogenous zone on the anterior, or front wall of the vagina, which correlated with the position of the urethra on the other side of that wall. Subsequent studies revealed a complex of blood vessels, nerve endings and remnants of the female prostate gland in the same area; and suggested that in a minority of women – particularly those with strong pelvic floor muscles – stimulation of this area could trigger powerful orgasms and the release of a small amount of fluid from the urethra that was not urine.  Word soon began to leak out about this magic button on the front wall of the vagina. Couples invested time, and - often fruitless - effort into finding it. Some feminists, meanwhile, claimed that the publicity surrounding the G-spot was an attempt by men to recoup the importance of vaginal penetration, after the spotlight had shifted to the clitoris during the sexual revolution of the 60s and 70s.  Evidence to support or refute the existence of the G-spot is patchy, and often overhyped. One study ‘disproving’ the existence of a G-spot was based on an MRI scan of just one woman. The debate is further obscured by a dispute about the correct terminology for the various inner regions of women’s private parts, and also where one structure starts and another ends.  However, there do seem to be physical differences between women who claim to experience vaginal orgasm and those who don’t. In 2008, Jannini published a study involving nine such responders, and 11 who said they’d never climaxed during penetrative sex alone. Ultrasound scans revealed a thicker area of tissue in the space between the vagina and the urethra in those that could.  At the time, Jannini concluded that this might well be evidence for the fabled G-spot. But further studies have prompted a rethink. “The word spot suggests a button; something that you can push to obtain an orgasm or pleasure,” he says. “It implies a concrete structure that’s either there or it’s not. No-one has been able to clearly describe such a structure as a spot.”  The clitoris could also be described as a two-headed penis; both are derived from the same embryonic tissue  So if it’s not a button, what else could it be? For a growing number of researchers the answer is simple: the clitoris. Although to most people, the clitoris is just a pea-shaped bobble under the surface of the skin, recent MRI studies suggest that the clitoris is far from diminutive. They reveal a large, bulbous structure around 9cm in length, which somewhat resembles a wishbone. It snakes its way around the outside of the vagina and up inside the pelvis alongside the urethra.  At the head of that wishbone is the glans – the external part that most people feel as the clitoris, and the most sensitive part. But the legs straddle the vaginal opening and extend into the labia.  It could also be described as a two-headed penis. Both the clitoris and the penis are derived from the same embryonic tissue; a swelling called the tubercle which emerges during the early stages of embryogenesis and then branches into either the clitoris and vulval tissue in girls, or the penis and scrotum in boys. But there are important differences: for one thing, the penis doesn’t grow in response to hormones like testosterone once puberty ceases, whereas the clitoris does. “It is not simply a little penis,” Jannini says. The vagina also responds to hormones, including oestrogen, which helps explain why women’s sexual response varies throughout their lives.  This complexity may explain why it has been so difficult to prove – or disprove – the existence of the G-spot; it’s not easy to stimulate the frontal wall of the vagina in isolation. You’re also likely rubbing up against the internal portions of the clitoris and the urethra as well.  Indeed, further research by Jannini and Odile Buisson at the Centre d’échographie in Saint Germain en Laye, France, has demonstrated this. They persuaded three women to either stimulate the front wall of their vaginas using a lubricated tampon, or use their fingers to stimulate the external parts of their clitoris - while using ultrasound to image what was happening beneath the skin. Vaginal penetration caused the internal parts of the clitoris and the tissue around the urethra to move and become engorged, whereas during manual masturbation, only the external parts of the clitoris were stimulated.  It gets even more complicated; in yet other women, vaginal penetration might simultaneously be stimulating both the external and the internal parts of the clitoris.  The woman had been born without a bladder, and had undergone extensive reconstructive surgery. The silver lining? She has incredible orgasms  In 2009, a 42-year-old woman presented at the clinic of Rachel Pauls, a urogynecologist based in Cincinnati, Ohio. The woman had been born without a bladder, and had undergone extensive reconstructive surgery to correct some of these problems. There is a silver lining to this cloud, however; “she has incredible orgasms,” Pauls says. Indeed, she told Pauls that she averages two orgasms every time she has sex – one through manual stimulation of her clitoris; the other through vaginal penetration alone. Pauls was particularly fascinated by her story, because the women’s urethra – and therefore the associated bundle of nerves and structures usually labelled the G-spot – wasn’t in the usual place. Additionally, the woman’s clitoris was positioned on the very edge of her vaginal opening. “It seemed likely that this was part of why she had such good orgasms,” Pauls says. The penis would brush against it with every thrust.  This sparked an idea. Pauls wondered if the size, and location of the clitoris in healthy women might influence the ease with which they orgasm during penetrative sex. So she and her colleagues recruited ten women who claimed rarely or never to achieve orgasm during sexual encounters, and twenty women who said they climax almost every time, and used an MRI scanner to take a detailed look at their clitorises. They found that the smaller the size of the pea-shaped glans, and the further the clitoris was from the vagina, the harder they found it to achieve orgasm.  Taken together, these studies imply that there are multiple routes by which women can experience an orgasm, be it through vaginal stimulation, clitoral stimulation, or both at once. Further studies by Komisaruk have revealed that projections from different regions of the female genitals – and indeed the nipples – all converge on the same general region of the brain, albeit in slightly different areas. “There’s a good neuro-anatomical basis for different types of orgasms and different types of sensations,” Komisaruk says. “This could account for why combining clitoral, vaginal and cervical stimulation seems to produce these more intense, complex and pleasurable orgasms that women describe.”  As for women who find it difficult to climax during penetrative sex – or indeed any sex – the message is simple: experiment.  As for women who find it difficult to climax during penetrative sex – or indeed any sex – Paul’s message is simple: experiment. “Women come to see me as patients and they’ll say ‘I can’t have vaginal orgasms, so there must be something wrong with me’. There’s nothing wrong with them. Everyone is a little different, so some women will have a lot of clitoral stimulation during sex, while for others it’s a little harder - so their partner may have to use their hands or a toy. But women should know that if they don’t have orgasms with straight out vaginal penetration, then that that’s normal.”  Jannini has an additional message for women: “Not only enjoy sex, but also enjoy knowing yourself and understanding who you are today, because probably tomorrow you will be different.” And don’t underestimate the infinite variety that’s on offer. “Do not think of the female body as a machine that can always deliver the same,” he says.  Share this story on Facebook, Google+ or Twitter.
From the G-spot to multiple orgasms, female sexuality has presented many mysteries. But as Linda Geddes discovers, radical experiments are finally revealing some answers.