Dopamine 'raises pleasure expectations, influences life choices'
17 November 2009
Researchers from the Wellcome Trust Centre for Neuroimaging at University College London found that increased levels of dopamine caused people to rate a particular holiday destination more highly than when they were not under the influence of dopamine.
"Our results indicate that when we consider alternative options when making real-life decisions, dopamine has a role in signalling the expected pleasure from those possible future events. We then use that signal to make our choices," said Dr Tali Sharot from the Wellcome Trust Centre and lead author on the study.
Dopamine is a neurotransmitter produced in several areas of the brain. Its role in reward learning and reward-seeking behaviour is well established by animal studies, but its role in humans is less understood.
In the study, researchers looked at the estimated pleasure of future events before and after subjects were given a drug called L-DOPA, which is known to enhance dopamine function in the brain and is commonly used to treat patients with Parkinson's disease.
They asked 61 people to rate their expectations of happiness if they were to take a holiday at each of 80 destinations, such as Greece and Thailand. They were then given L-DOPA or a placebo and asked to imagine going to those destinations.
The next day, participants were asked to choose between a series of paired destinations that they had initially assigned with equal ratings. One of the pair was imagined under the influence of L-DOPA the day before, while the other had been imagined under the placebo. They were then asked to rate the full set of 80 destinations again.
The researchers found that the destinations imagined under the influence of L-DOPA were rated higher on the first day, and that increase also affected the participants' selections the following day.
"We had reason to believe that dopamine would enhance expectations of pleasure in humans, but were surprised at the strength of this effect," said Dr Sharot. "The enhancement lasted at least 24 hours and was evident in almost 80 per cent of the subjects."
The researchers say the findings could help us understand how pleasure expectation can go awry, such as in drug addiction.
Image: Bangtao Beach, Laguna, Phuket, Thailand. Credit: Lewi Hirvela on Flickr
Reference
Sharot T et al. Dopamine enhances expectation of pleasure in humans. Curr Biol 2009 [Epub ahead of print].