Some of us work hard, others are slackers -- for a long time the reason behind radically different work ethics has been a mystery. But new research reveals that dopamine levels in three different areas of the brain influence our willingness to work.
The study, which is to be published in tomorrow's issue of the Journal of Neuroscience, used positron emission tomography (PET) to image the brains of a cross-section of participants, from go-getters to slackers. The participants were asked to choose from a range of tasks -- some simple, others far more difficult -- in exchange for varying monetary rewards.
The researchers found that people willing to work hard to earn rewards had higher release of dopamine -- a "feel-good" neurotransmitter -- in areas of the brain known to play an important role in reward and motivation: the striatum and ventromedial prefrontal cortex. People who weren't keen to work, however, had higher levels of dopamine in part of the brain that plays a role in emotion and risk perception, called the anterior insula. David Zald, one of the researchers, explained to EurekAlert:
"Past studies in rats have shown that dopamine is crucial for reward motivation, but this study provides new information about how dopamine determines individual differences in the behaviour of human reward-seekers."
The fact that dopamine has opposing effects in different parts of brain is an interesting, and in fact troublesome, finding. Many existing psychotropic medications -- for instance, those used to treat attention-deficit disorder -- affect absolute dopamine levels. This finding suggests that shifting dopamine distribution might be far more important than merely adjusting the total amount -- but such an effect is currently impossible to achieve.
If the researchers can extend the work to get to the bottom of how, exactly, dopamine distribution affects mood, the findings could have a huge impact on the treatment of attention-deficit disorder, depression and schizophrenia in the future. [Journal of Neuroscience via EureakAlert]
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