Activation of a reward-processing brain region peaks in the morning and evening and dips at 2 p.m., finds a study of healthy young men published in The Journal of Neuroscience. This finding may parallel the drop in alertness people tend to feel in mid-afternoon.
Greg Murray and colleagues compared activation of the brain's reward system in 16 men during a gambling task at 10 a.m., 2 p.m. and 7 p.m. They found that activation in the left putamen was lowest in the early afternoon. The result contrasts with previous research showing that people report being in the best mood -- a subjective measure of reward activation -- at this time. The authors suggest that activation is greater in the morning and evening because rewards are not expected at these times.
Understanding the timing of reward response could have implications for the treatment of disorders in which symptoms fluctuate throughout the day, such as depression, substance abuse and sleep disturbances. This work also calls into question neuroimaging studies that do not control for or report the time of day when scanning took place.
Article: Time of day differences in neural reward functioning in healthy young men
Corresponding author: Greg Murray (Swinburne University of Technology, Australia), firstname.lastname@example.org
The Journal of Neuroscience (JNeurosci) is the flagship journal of the Society for Neuroscience. JNeurosci publishes papers on a broad range of topics in neuroscience in a print edition each Wednesday and recently began publishing early-release PDFs of studies online shortly after acceptance.
About The Society for Neuroscience
The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 37,000 members in more than 90 countries and over 130 chapters worldwide.