The first scan revealing exactly what happens inside a woman’s brain when she has an orgasm has been developed by scientists.

They have discovered that sexual arousal numbs the female nervous system to such an extent that she doesn’t feel as much pain – only pleasure.

American researchers found that the orgasm affects up to 30 different parts of the brain including those responsible for emotion, touch, joy, satisfaction and memory.

The team from Rutgers University, New Jersey, now hope to be able to map what typically happens inside a woman’s brain when she has an orgasm.

Watch this: Meg Ryan in the fake orgasm scene in When Harry Met Sally, the 1989 hit movie

This could enable them to pinpoint what is going wrong among those with problems of sexual dysfunction or low libido.

They also want to build up a similar picture for men so they can compare how the sensation affects the male and female brains.

Evidence suggests women experience longer orgasms than men, and can have several in quick succession.

The researchers asked eight women to stimulate themselves while lying under a blanket inside an Magnetic Resonance Imaging (MRI) scanner, a tunnel-like machine often used to detect brain tumours.

Most women took less than five minutes to reach an orgasm although some took as long as 20.

During that time, the MRI scanner took images of their brain every two seconds to show which parts became active during the orgasm.

The scientists found that two minutes before the orgasm, the brain’s reward centres become active, the areas usually activated when eating food and drink.

Immediately before they reached the peak, other areas of the brain became affected such as the sensory cortex, which receives ‘touch’ messages from parts of the body and the thalamus, which relays signals to other parts of the body.

Once the orgasm has started other parts of the brain are activated such as those responsible for emotion - the cingulate cortex and the insula.

The final part of the brain to be activated is the hypothalamus, the ‘control’ part of the brain which regulates temperature, hunger, thirst and tiredness.

At the same time another area responsible for pleasure is activated - the nucleus accumbens - as well as the caudate nucleus, which is responsible for memory.

The scientists found that the pattern of activity was the same for all women in their experiment.

Barry Komisaruk, professor of psychology at Rutgers University, in New Jersey, said: 'In women, orgasm produces a very extensive response across the brain and body.

'In one experiment we asked women to self-stimulate and then raise their hands when they orgasmed.

'Some women raised their hands several times each session, often just a few seconds apart.

'So the evidence is that women tend to have longer orgasms and can experience several in rapid succession.'

A woman’s orgasm last an average of 10-15 seconds, whilst a man’s is thought to last for just six seconds.

But only within the past few decades has society accepted that women actually enjoy sex - rather than it just being a function for them to give birth.

Until the late 1960s, many scientists and doctors refused to believe that they could actually have an orgasm.

Last week TV presenter Stephen Fry provoked outrage amongst feminists by claiming that women are unenthusiastic about sex, and see it only as ‘the price they are willing to pay for a relationship’.

Many still insist that women with a low sex drive are not suffering from a medical condition - they are either tired or not in the mood.