The chip works by sending tiny shocks from implanted electrodes in the brain.

The technology has been used in the United States to treat Parkinson's disease.

But in recent months scientists have been focusing on the area of the brain just behind the eyes known as the orbitofrontal cortex - this is associated with feelings of pleasure derived from eating and sex.

A research survey conducted by Morten Kringelbach, senior fellow at Oxford University's department of psychiatry, found the orbitofrontal cortex could be a "new stimulation target" to help people suffering from anhedonia, an inability to experience pleasure from such activities. His findings are reported in the Nature Reviews Neuroscience journal.

Neurosurgery professor Tipu Aziz, said: "There is evidence that this chip will work. A few years ago a scientist implanted such a device into the brain of a woman with a low sex drive and turned her into a very sexually active woman. She didn't like the sudden change, so the wiring in her head was removed."