女性高潮時 活躍大腦30部位

美國研究人員使用核磁共振攝影，首度拍攝到女性性高潮時腦部活動影像，發現腦部高達30個部位會在高潮時陸續進入強烈活動狀態，讓神經系統因愉悅而麻木，甚至暫時喪失痛覺。
新澤西州羅格斯大學研究人員發現，性高潮會影響女性大腦30個不同部位，分別職司情緒、觸覺、喜悅、滿足與記憶。他們希望能夠繪出女性這種時刻的大腦狀態，進而瞭解部分女性面臨性功能障礙或性冷感的原因。

研究人員也希望繪出男性的大腦狀態圖，以比較性高潮影響男女大腦狀態的差異。研究顯示，女性性高潮持續的時間不但比男性長，而且可連續快速出現多次。女性性高潮平均持續10到15秒，男性6秒。

研究人員要求16名女性志願者蓋著毯子躺在核磁共振攝影機上，以自我刺激方式達到高潮。實驗顯示，雖然在這種環境下，多數女性進入性高潮所需時間不到5分鐘，部分女性則需要20分鐘。

高潮前2分鐘，大腦的酬償中樞開始活躍。此外，高潮即將出現時，大腦的其他部位也會受到影響，包括負責接收身體各部位及丘腦觸覺訊息的知覺腦皮層。高潮開始後，大腦的其他部位隨之啟動，包括職司情緒的扣帶腦皮層及腦島。最後啟動的大腦部位是管理溫度、飢餓、口渴及疲倦感的下丘腦。在此同時，分別職司愉悅、記憶的阿肯伯氏核與尾狀核也會相繼啟動......


This week we report on the continuing debate about female ejaculation: is it real, and if so why does it happen?

See: Everything you always wanted to know about female ejaculation (but were afraid to ask)

Ejaculation is just one of the aspects of female sexuality that are being demystified by research. In particular, the female orgasm, the subject of so many myths and folk beliefs, is gradually being understood.

Following some intense field research, here are some of the key facts about the female orgasm, as revealed by modern science.

The G spot is real

The G spot is a small region in the vagina that, if stimulated, can produce wildly intense orgasms – or so the popular claim goes. However, for decades, strong evidence for the region's existence was harder to find than the spot itself.

However, in 2008, an Italian research team found anatomical differences between women who could have G-spot orgasms and women who couldn't; apparently solving the mystery. The researchers have since begun teaching women with G spots how to put them to use.

See: Ultrasound nails location of the elusive G spot

The brain switches off

It's folk wisdom that people can't think straight when they have sex on their minds, but when women have an orgasm most of their brains switch off.

A brain scanning study showed that many areas of women's brains were deactivated during orgasm, including those involved in emotion. The effect was less striking in men, but that may be because male orgasms are so short they are hard to detect in a brain scan.

See: Orgasms: A real turn-off for women

Many women can't have orgasms

According to a 1999 survey, around 43 per cent of women in the US have some sort of problem with their sex lives (Journal of the American Medical Association, vol 281, page 537).

Female sexual dysfunction (FSD) is so common that the very idea that it is a medical disorder has come under attack. If nearly half the female population has a problem, say critics, does that mean it is our society that is dysfunctional?

Even so, efforts to develop drugs to treat it are underway. The impotence drug Viagra has had mixed results in women, but there are many other avenues being explored.

See: What women want

Genes affect orgasm frequency

According to the first genetic study of the female orgasm, up to 45 per cent of the variation in women's ability to have them could be down to genes.

Many women never have orgasms during intercourse, and some also cannot have them through masturbation. Some of this may be down to external factors like upbringing, but the study showed the genetic factor is significant.

See: Genes blamed for fickle female orgasm

Technology can help

Perhaps the most extreme solution is the so-called "orgasmatron"; an implant inserted into the spinal cord, which stimulates the user when switched on via a remote control.

Despite an initial struggle to find subjects for clinical testing, the device is now in development.

See: Push my button

Some mystery remains

The female orgasm is a puzzle for evolutionary biologists. It is unclear why women should have orgasms at all, and it is particularly baffling that so many women should be unable to have orgasms during penetrative sex, but able to have them by masturbation.

According to researcher Elisabeth Lloyd, that implies that female orgasms are an evolutionary accident. Like male nipples, they persist simply because there is no good reason to get rid of them.

See: The case of the female orgasm