Twenty-five years after she made the G-spot famous, Professor Beverly Whipple is still probing the mysteries of the female orgasm. She has shifted her focus higher up the body - to the brain - exploring the areas that light up when women climax. But the motivation for her research remains the same: "Orgasm is a remarkable phenomenon. It's one of life's most intriguing experiences."
Whipple, of the College of Nursing at Rutgers University in New Jersey, also remains inspired by the many women who have helped her over the decades to delve into this poorly studied aspect of life. Her latest brain research on orgasms has relied on the good will of a variety of women, including those with spinal injuries caused by gunshot wounds and those who can climax just by thinking about it.
Not only did the women have to stimulate themselves in the laboratory, they had to do it lying as still as possible inside a giant magnet, so their brain activity could be captured on an MRI scan. "It's just unbelievable the things they will do for science," says Whipple, in a phone interview from the US.
The pioneer sex researcher Alfred Kinsey claimed more than 50 years ago that orgasm involved the entire nervous system and all parts of the body.
It may have seemed like an exaggeration, says Whipple, who will be in Sydney this month to address the World Congress for Sexual Health. But her recent research with colleagues indicates that orgasm is a very complex neurological event, with a large number of brain areas activated during the experience. "This may be the reason why most drugs impair, rather than improve sexual response," she says.
The team has also identified three nerve pathways not previously linked to female sexuality. They carry sensations from the vagina, cervix and uterus to the brain.
"There is good evidence that activation of these nerves, by physical stimulation of these uniquely female organs, can generate orgasms," says Whipple, who summarises the research in a new book, The Science of Orgasm, with colleagues Professor Barry Komisaruk and Carlos Beyer-Flores.
Whipple helped discover the controversial G-spot, and named it after the German gynaecologist Ernst Grafenberg, during the 1970s when she was training women how to improve their pelvic muscle control.
An examination of more than 400 women revealed an erogenous zone located about a third of the way up the vagina, on the front side. Pressure on the underlying tissue, which is near the female prostate gland, causes it to swell, triggering orgasm in some women.
Many doctors have expressed scepticism about its existence, but that's not surprising, says Whipple. The region is blocked by the metal speculum used to examine women internally. And the G-spot has to be manipulated to be felt. "Doctors can't sexually stimulate their patients. That's why they didn't find it," she says.
Not all women are sensitive in this region, adds Whipple. And it is only likely to be aroused by pressure during intercourse in some positions, when the woman is on top, or the man enters from behind. This may partly explain why only about 30 per cent of women experience orgasm during intercourse.
For their research, Whipple and her colleagues use a specially designed small stimulating rod which is attached with velcro to a diaphragm that covers the cervix. The women control its movement.
"Women using this device tell us that when they pull outward with the stimulator, it produces a very pleasurable suction on the cervix that they have never experienced before," says Whipple. One woman described these cervical-based orgasms as like a "shower of stars".
The clitoris has been a focus of attention, because it is easy to stimulate, but clitoris-based orgasms tend to be restricted to around this region. Research also shows the vagina balloons out in this case and the uterus pulls up.
Vaginal orgasms, triggered by the G-spot, are felt deeper inside. The uterus pushes down. "It's like a bearing down sensation," says Whipple.
The different nature of the orgasms is probably due to the four different nerves systems carrying sensations from these different regions to the brain. The pudendal nerve, the same nerve that provides penile sensation, is linked to the clitoris. The vagina is supplied by the pelvic nerves, and the cervix and uterus by the hypogastric, pelvic and vagus nerves. Combined stimulation of all regions can produce more encompassing "blended" orgasms, says Whipple.
Publicity about the G-spot may have led to a feeling of inadequacy for men and women who couldn't find it. But Whipple says her intention was never to suggest this was a must-have experience. When it comes to sexual pleasure, no way is best. "Different people have different tastes. It's what feels good to you," she says.
Men and women differ in their sexual responses. Men move in order from desire to arousal to orgasm. Women are more complicated, says Whipple. "They can experience sexual arousal, orgasm and satisfaction without desire, and they can experience desire, arousal and satisfaction without orgasm."
Sexual problems can occur if people have a goal-oriented approach to sexual activity, if they think of it as a staircase, that starts with touching and ends at orgasm on the top step. "If the sexual experience does not lead to orgasm, one or both partners feel unsatisfied," says Whipple.
A better way to think about it is like a pleasure circle, where any activity has its place along the perimeter. "Each is an end in itself and satisfying."
Whipple also says people can experience orgasm - an intense pleasurable response - from stimulation of many parts of their bodies, not just the genitals.
Stuart Meloy, an American doctor treating people for chronic back pain, revealed last year that when he applied electrical stimulation through the spine, 10 out of 11 of his female patients reported experiencing orgasms.
People with spinal cord injuries also say that when hypersensitive skin near their injury is stimulated in the right way, by the right person, they have pleasurable orgasmic feelings that can seem to emanate from the genitals. Some of Whipple's earlier research demonstrated that these people also had increased heart rates and blood pressure, just as in genital orgasm.
One woman she studied had been told by her doctors she could not experience orgasm because she had no feeling below her breast. Yet she experienced six orgasms during her three 12-minute sessions of genital and non-genital stimulation in the laboratory.
"She was so thrilled and I was so happy for her. It was a moving experience," recalls Whipple.
For its recent studies of brain activity the team chose women with spinal injuries who'd had a gunshot wound, rather than compressive damage, to ensure they had no activity left in the spinal cord.
When these women used the laboratory device to stimulate the vagina and cervix, the part of their brains where sensations from the vagus nerve are recorded lit up. This shows sensations can go directly from these regions to the brain, bypassing the spinal cord, the team concluded.
Some of these women, as well as able-bodied ones and women who can climax through imagery alone, also experienced orgasm, and the researchers were able to compare their brain scans before, during and after the event.
Many of the same areas lit up in the three groups, including regions linked to the experience of pain and those triggered by pleasure-producing drugs like cocaine. A third area involved in the production of the hormone oxytocin, which is secreted in large amounts during orgasm in women and stimulates uterine contractions, was also active.
The research is still in its infancy, says Whipple. "Where in the brain orgasm is produced is an unanswered but, we hope, not unanswerable question."