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Professor tests hypothesis about the functions of dopamine

Campus Correspondent

Published: Friday, December 7, 2012

Updated: Friday, August 23, 2013 17:08

 A UConn researcher is shaking the belief that the neurotransmitter, dopamine, is linked to pleasure with a series of experiments.

Three decades ago, scientists at the National Institute on Drug Abuse made a groundbreaking discovery when they concluded that dopamine, a neurotransmitter in the brain, was linked to pleasure. Society widely accepted these findings, and dopamine soon became a hot topic that expanded outside the realm of the scientific world and into popular culture. However, recent research suggests a new theory of dopamine’s role, and one UConn professor is at the forefront of this discovery.

John Salomone, a psychology professor at UConn, tested his hypothesis that dopamine levels affect motivation rather than pleasure in a series of experiments in which animals had to choose between two rewards: one small but easily accessible, the other large but more challenging to reach. As a result of such experiments, Salomone concluded that higher dopamine levels directly impacted motivation levels. Thus, animals with low dopamine levels lacked motivation.

“Interfering with dopamine transmission increased selection of tasks that had low work requirements, essentially inducing a bias towards low expenditure of effort,” Salomone said.

Although, animals aren’t the only ones that experience a flux in motivation as dopamine levels rise and fall. Humans, too, experience similar effects, Salomone explains. The effects of dopamine are especially apparent in depression sufferers, whose severely low levels of dopamine cause them to lose all desire to seek rewarding behaviors in which work is required, such as socializing with friends. The breakthrough in Salomone’s research is a much-celebrated effort that came 15 years after he first began studying dopamine as a graduate student at Emory University. “My advisor studied dopamine, and that got me started,” Salomone said. “I did my dissertation on the behavioral functions of dopamine systems, and have been studying it ever since.”

Salomone first became aware of the cracks in the conventional dopamine conceptions when some of his early studies indicated that increased dopamine levels didn’t always occur in times of happiness. In contrast, high levels of dopamine in both humans and animals were sometimes present in times of violence and stress, such as when an animal lost a fight with another animal or when soldiers with PTSD heard gunshots.

Salomone, however, isn’t alone in his perspective regarding dopamine. The theory that dopamine levels influence motivation is becoming increasingly mainstream amongst the scientific world, yet remains relatively unknown to much of the general population.

“The whole idea that dopamine is the ‘pleasure chemical’ in the brain has gone overboard. It is almost an urban legend at this point,” Salomone said. “I think the lesson needs to be that complex scientific findings should not be reduced to simple ideas that may be popular, and easy to understand, but do not really capture the phenomenon being studied.”

To combat this lack of knowledge from the general public, more and more research findings regarding dopamine have been published that are accessible to the entire population. In addition, further research, especially on the medical front, continues to advance the amount of information available about dopamine and its effects. For example, Michael Treadway, a clinical psychology researcher at Harvard University, is currently studying the neural mechanisms pertaining to depression, which may someday lead to treatment for the condition.

As dopamine research continues to make headway, Salomone’s contributions will be remembered as an integral role in the development of such a psychological breakthrough. But for now, though, he plans to play no part in publicizing his findings. “I don’t intend to write a book on this subject--not for a few years, anyway. I prefer scientific writing for now,” he said. And Salomone’s passion for and prominence in science is one fact that can’t be argued.


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