People who become euphoric over music unleash dopamine, a brain chemical that also induces the sense of reward that comes from food, psychoactive drugs and money, an unusual study says.

   McGill University researchers in Montreal, Canada, recruited eight volunteers aged 19-24 among 217 people who responded to advertisements requesting people who experienced "chills" -- a marker of extreme pleasure -- when listening to music.

  After careful selection, the volunteers were put into a positron emission tomography (PET) scanner, which is able to spot a tagged chemical, raclopride, that works on dopamine receptors in brain cells.

   They were also wired up to sensors that measured them for heartbeat, respiration, temperature and skin conductance.

   Listening to their favourite piece of spine-tingling music, the volunteers showed a rush of physical activity and also unlocked a release of dopamine in the striatum area of the brain.

   The effect occurred even in anticipation, before the "chill" peak occurred.

   But no such dopamine surge was seen when the volunteers listened to neutral music which, previous tests showed, was known to leave them emotionally cold.

   Seeking to find out more, the scientists then put the volunteers in a frequency magnetic resonance imaging (fMRI) scanner, which highlights flows of blood in the head, thus showing which part of the brain is being activated.

   A part of the striatum known as the caudate was involved during the anticipation phase. But during the peak emotional response, a different striatum area known as the nucleus accumbens was involved.

   The results shed light on the exclusive regard that humans have for music, say the researchers.

   Reward sensation could help explain why music is liked in every society -- but also why appreciation of it is such an individual or cultural thing.

   Scientists consider dopamine to be an ancient chemical that is essential for survival.

   It dishes out feel-good jolts in response for life-supporting actions such as eating and for acquiring "secondary" tangibles such as money. The mechanism can also be triggered by drugs.

   But music is abstract, is not directly essential for survival and is not one of these "secondary" or conditioned sources of reward, says the study.

   "(Abstract) stimuli have persisted through cultures and generations, and are pre-eminent in most people's lives," it says.

   "Notably, the experience of pleasure to these abstract stimuli is highly specific to cultural and personal preferences, which can vary tremendously across individuals."

   One possible explanation for this is because of the emotions invoked by music -- "expectations, delay, tension, resolution, prediction, surprise and anticipation," among others.

   The paper, headed by Valorie Salimpoor and Robert Zatorre, is published online by the specialist journal Nature Neuroscience. (AFP)