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Summary :
This paper summarizes a research program that began in the 1970s with the re-discovery and naming of the Grafenberg spot by Drs. John Perry and Beverly Whipple. The spot in question is a sensitive area, which is felt through the anterior vaginal wall, half-way between the back of the pubic bone and the cervix, along the course of the urethra described in the 1950s by Dr Ernest Grafenberg, hence the name of "G spot". Perry and Whipple also developed a continuum of sexual response in women, which explains vulva, uterine and blended orgasms and the neural pathways involved in different types of sexual response in women. In addition to identifying and publishing about the G spot, they also published about the phenomenon of female ejaculation, an expulsion of fluid from the urethra that is chemically different from urine. They found that the female ejaculatory fluid contained Prostatic Acid Phosphatase, which was not found in urine from the same subjects. More recently, researchers have tested and found Prostatic Specific Antigen in the female ejaculation but not in urine from the same women. Whipple then investigated the adaptive significance of the area of the Grafenberg spot. Based on research conducted on animals, she found that vaginal self-stimulation in women produces a strong pain blocking effect, that is, an elevation in pain thresholds but not tactile thresholds. The elevation in pain thresholds is higher when the vaginal self-stimulation is applied in a pleasurable manner and even higher when the subject reports that she has had an orgasm. This pain blocking effect also takes place naturally during labor. It is hypothesized that childbirth would be much more uncomfortable without this natural pain-blocking effect, which is activated as the cervix dilates and pressure is increased in the birth canal as the fetus emerges.

Sexual response was then tested in women who reported orgasm from fantasy alone and on women with complete spinal cord injury. It has been documented in the laboratory that women can experience orgasm from anterior vaginal wall self-stimulation (Grafenberg spot area), from cervical self-stimulation and from fantasy alone. Women with complete spinal cord injury are also able to experience orgasm from anterior vaginal wall, cervical, and hypersensitive area self-stimulation. Based on these studies, the definition of orgasm needs to be re-evaluated. As a continuation of this research program, Whipple, Komisaruk and their colleagues have been conducting PET scans of the brain during orgasm in women with complete spinal cord injury and have identified an additional neural pathway that by-passes the spinal cord and travels directly from the genitals to the brain. Through the sensory vagus nerves. Recommendations for future research in the areas of sexuality are offered, with an emphasis on pleasure-oriented rather than goal-oriented sexual expression.