ANN ARBOR—If you've ever felt lackadaisical to start a new project, focus on imagining the joy of completing it, say University of Michigan researchers.

Both are a function of dopamine, which explains the motivation to start and the satisfaction of finishing work, they say.

In a new study, U-M researchers Arif Hamid and Joshua Berke, professor of psychology and biomedical engineering, argue that dopamine levels continuously signal how good or valuable the current situation is regarding obtaining a reward. This message helps people decide how vigorously to work toward a goal, while also allowing themselves to learn from mistakes.

"We provide a new theoretical account for how dopamine affects learning (what to do later) and motivation (getting fired up to go now) simultaneously," said study lead author Hamid, U-M neuroscience doctoral student.

For many years, researchers have known that dopamine is important for arousal, movement, mood and executing activities with haste and vigor. Aspects of these normal dopamine functions are highlighted in disorders, such as Parkinson's disease and depression. Drugs that elevate brain dopamine levels, like cocaine or amphetamines, produce euphoric feelings of well-being, in addition to heightened arousal and attention.

Aside from affecting immediate mood and behavior, dopamine also produces changes in the brain that are persistent, sometimes lasting a lifetime.

"This is basically how we stamp in memories of what the smell of cookies or the McDonald's sign mean: predictors of delicious, calorie rich rewards," Hamid said.

Read the full article "Dopamine: New theory integrates its role in learning, motivation" at