Scientists have observed for the first time what goes on inside a woman's brain during orgasm, and it is as complicated as many men suspected.

Neuroscientists in New Jersey have used MRI scanners to discover that 30 different parts of a woman's brain fire up during orgasm and the pleasure is so great it can stop the lucky lady from feeling pain. This is due to parts of her nervous system shutting down, making the woman less aware of pain sensations.

MRI scans show a woman's brain lights up like a Christmas tree during an orgasm.

Volunteers brought themselves to orgasm inside an MRI machine, which scanned the brain during the process. For some this took 20 minutes, while most achieved their goal in under five.

Brain areas responsible for emotion, touch, satisfaction and memory are involved.