Whether someone is a "go-getter" or a "slacker" may depend on individual differences in the brain chemical dopamine, according to new research in the May 2 issue of The Journal of Neuroscience. The findings suggest that dopamine affects cost-benefit analyses.
The study found that people who chose to put in more effort - even in the face of long odds - showed greater dopamine response in the striatum and ventromedial prefrontal cortex, areas of the brain important in reward and motivation. In contrast, those who were least likely to expend effort showed increased dopamine response in the insula, a brain region involved in perception, social behavior, and self-awareness.
Researchers led by Michael Treadway, a graduate student working with David Zald, PhD, at Vanderbilt University, asked participants to rapidly press a button in order to earn varying amounts of money. Participants got to decide how hard they were willing to work depending on the odds of a payout and the amount of money they could win. Some accepted harder challenges for more money even against long odds, whereas less motivated subjects would forgo an attempt if it cost them too much effort.
In a separate session, the participants underwent a type of brain imaging called positron emission tomography (PET) that measured dopamine system activity in different parts of the brain. The researchers then examined whether there was a relationship between each individual's dopamine responsiveness and their scores on the motivational test described earlier.