Kayt Sukel masturbated for a fMRI:
Over 30 areas of my brain are activated as I move from start to finish, including those involved in touch, memory, reward and even pain. As [researcher Barry] Komisaruk expected, the imagined clitoral touches and Kegel exercises activated the same brain areas as real ones, albeit with somewhat less blood flow. The [prefrontal cortex], however, showed more activation when touches and pelvic squeezes were imagined compared with those that were real. He suggests this heightened activation may reflect imagination or fantasy, or perhaps some cognitive process that helps manage so called "top-down" control – the direct regulation by the brain of physiological functions – of our own pleasure.
(Image: Kayt Sukel's brain at the moment of orgasm. "You can see from the extent of activity that an orgasm is a whole-brain experience. Activation in the prefrontal cortex (A) is clearly visible, as well as activity in the anterior cingulate cortex (B), thought to be involved in the experience of pain.")