According to the new research, varying dopamine responses in the brain may be the reason some people work around the clock while others prefer to snooze the day away. The brain’s responsiveness to dopamine, a neurotransmitter critical for movement, motivation and reward, could even be an innate trait.
To gauge the participants attitudes towards hard work, the researchers asked each one to play a game in which pressing a button was correlated with winning an award. While easy tasks reaped small monetary rewards, more challenging ones could result in larger sums. Some participants accepted harder challenges against greater odds, while the “slackers” of the group abandoned attempts involving too much effort.
The participants then underwent positron emission tomography (PET) scans that measured dopamine activity in different parts of the brain.
What the scientists found when looking at the scans somewhat surprised them. People who put in more effort showed greater dopamine response in the striatum and ventromedial prefrontal cortex, brain areas involved in reward and motivation. People without the go-get-‘em attitude had greater dopamine levels in the insula, a brain area involved in emotion and risk perception.
The finding that dopamine can have different effects in different parts of the brain could complicate treatments for attention-deficit disorder, depression, and schizophrenia—which all make use of psychotropic medications that affect dopamine levels.
“Imagine how valuable it would be if we had an objective test that could tell whether a patient was suffering from a deficit or abnormality in an underlying neural system,” David Zald, one of the study’s authors, said in a statement. “With objective measures we could treat the underlying conditions instead of the symptoms.”
The study is published in the Journal of Neuroscience.