TOKYO (AFP) - A smoker's craving to light up can be tamed by carefully targeted magnetic fields applied to the brain, a senior researcher from a Japanese-Canadian team said today.

Scientists managed to zoom in on the exact spots that drive the need for nicotine, noting that a mental connection made when a smoker is able to have a cigarette markedly increases the desire to spark up.

They found that by interrupting this connection, the addict was better able to control his or her cravings.

"Cabin attendants who smoke say they feel stronger cravings for cigarettes as they approach landing times, no matter whether their flights are long-distance or not," Takuya Hayashi said from Kobe in western Japan.

"Our study shows the urge for smoking is not only about if smokers are running out of nicotine," said Hayashi, of Japan's Riken Centre for Molecular Imaging Science, noting a neural mechanism was also playing a role.

MRI images showed two regions in the frontal cortex, the part of the brain that controls decision-making, interact and increase the urge to smoke, according to the study, carried out jointly with Alain Dagher of the Montreal Neurological Institute at Canada's McGill University.

Imaging of the brains of ten smokers who watched video footage of people puffing away showed increased activity in the orbitofrontal cortex (OFC), a region of the brain just behind the eyes.

The dorsolateral prefrontal cortex (DLPFC), which is located higher up, was found to become active if the smoker knows cigarettes will be available immediately after the experiment.

Higher activity in the DLPFC boosted activity in the OFC, thereby increasing the desire to smoke, the study found.

When researchers targeted the DLPFC with magnetic stimulation - effectively limiting it - activity in the OFC became independent of the availability or otherwise of tobacco, thus reducing cravings.