The researchers report results that add to our knowledge of how human behavior is shaped by the default mode network, a specific network of brain regions with both resting and task states. The article, “Reward Enhances Connectivity Between the Ventral Striatum and the Default Mode Network” was published on June 18, 2022, in NeuroImage. The authors are Ekaterina Dobriakova, Ph.D. from the Kessler Foundation and David V. Smith, Ph.D. from Temple University.
The default mode network (DMN), comprising the posterior medial cortex, medial prefrontal cortex, and lateral temporal parietal regions, has been shown to be involved in many task-related behaviors. Studies show that DMN activity increases during inward-directed thinking and decreases during outward-directed tasks that require focused attention. Although there is evidence for a role of the DMN in shaping behavior, little is known about how task-related changes in the DMN affect connectivity to other brain regions. For example, while some observations suggest an indirect relationship between the DMN and the striatum, how the DMN and the striatum interact during tasks remains unclear.
To further explore the functions of the DMN, Dr. Dobryakova and Smith applied a new analysis of the reward task, using behavioral and neuroimaging data from 495 randomly selected individuals in the Human Connectome Project, an open database of healthy participants. The goals of the network-based psychophysiological interaction analysis were twofold, according to Dr. Dobryakova, senior researcher at the Foundation’s Center for Traumatic Brain Injury Research. “First, to test the effects of reward on connectivity between the DMN and the striatum; and second, whether this connectivity is associated with behavioral and personality characteristics relevant to reward processing,” she explained.
Consistent with other studies, during the task, they observed decreased DMN activation and relative increased activation of other networks. “In particular, we found that the reward experience enhanced connectivity between the DMN and the ventral striatum,” Dr. Dobryakova reported, a DMN-specific effect. We were also surprised that the strength of this connection correlates with personality characteristics related to openness.”
A greater understanding of the proper functioning of the brain will influence future research and care for individuals with neuropsychiatric syndromes. “Improving our understanding of the interaction of the DMN with other brain networks has the potential to aid clinical research in better treatments for common syndromes such as depression, substance abuse and schizophrenia,” Dr. Dobryakova concluded.
This research was supported by grants from National Institutes of Health grants R21-MH113917 (DVS), R03-DA046733 (DVS), RF1-AG067011 (DVS), R01-NS121107 (ED).