New experiences trigger a spurt of dopamine from the midbrain, but some individuals react more strongly than others do. Researchers at Vanderbilt University have identified a cellular mechanism that might underlie these differences.
Dr. David H. Zald and colleagues report that people who have a tendency to favor novelty have lower-than-average availability of a receptor that inhibits dopamine's release from neurons. Lower receptor availability translates into heightened dopamine release, which likely stimulates the activity of reward circuits, the researchers say.
The team ranked 34 study participants, aged 18 to 38, on the basis of novelty-seeking personality traits, which include impulsiveness, willingness to spend money freely, and a preference for spontaneous action. Using positron emission tomography imaging with the radiochemical [18F] fallypride, Dr. Zald and colleagues found a strong link between novelty-seeking behavior and low dopamine receptor availability in the midbrain, which includes sections of the pathways that influence reward and movement.
The findings accord well with the results of previous animal studies and suggest that the availability of dopamine-regulating receptors in midbrain neurons may partly determine responsiveness to novelty and other rewards.
The Journal of Neuroscience 28(53):14372-14378, 2008. [Full Text (PDF, 1.6MB)]