Summary: Study reveals how reward improves connectivity between the ventral striatum and the default mode network, which impacts behavior.
Source: Kesler Foundation
The researchers reported findings that add to our knowledge of how human behavior may be shaped by the Default Mode Network, a specific network of brain regions with resting and task-related states.
The Default Mode Network (DMN), which includes the posterior medial cortex, medial prefrontal cortex, and lateral temporal-parietal regions, has been shown to engage in several task-related behaviors. Studies show that DMN activity increases during inward-directed thinking and decreases during outward-directed tasks requiring focused attention.
Despite evidence for a role of the DMN in shaping behavior, little is known about how task-related changes in the DMN influence connectivity with other brain regions. For example, while some observations indicate 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, Drs. Dobryakova and Smith applied a new analysis to the reward task, using behavioral and neuroimaging data from 495 randomly selected individuals from the Human Connectome Project, an open-access database of healthy participants.
The goals of this network-based psycho-physiological interaction analysis were two-fold, according to Dr. Dobryakova, principal investigator at the Foundation’s Center for Traumatic Brain Injury Research.
“First, to test the effects of reward on the 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 a decrease in DMN activation and a relative increase in the activation of other networks.
“Specifically, we found that the reward experience enhanced the connectivity between the DMN and the ventral striatum,” Dr. Dobryakova reported, “an effect specific to the DMN. We were also surprised that the strength of this connectivity was correlated with openness-related personality characteristics,” she added.
A better understanding of how a healthy brain works will influence future research and care for people with neuropsychiatric syndromes. “Improving our understanding of the interaction of DMN with other brain networks has the potential to aid clinical research into better treatments for common syndromes such as depression, substance abuse and schizophrenia,” concluded Dr. Dobryakova.
Funding: This research was supported by National Institutes of Health Grants R21-MH113917 (DVS), R03-DA046733 (DVS), RF1-AG067011 (DVS), R01-NS121107 (ED).
About this neuroscience research news on reward and behavior
Author: Caroline Murphy
Source: Kesler Foundation
Contact: Carolann Murphy – Kessler Foundation
Image: Image is in public domain
Original research: Free access.
“Reward enhances connectivity between the ventral striatum and the default mode network” by Ekaterina Dobryakova et al. NeuroImage
Reward improves connectivity between the ventral striatum and the default mode network
The Default Mode Network (DMN) has been theorized to participate in a range of social, cognitive and affective functions. Yet previous accounts fail to account for how the DMN contributes to other regions of the brain depending on the psychological context, thus rendering our understanding of DMN function incomplete.
We have addressed this gap by applying a novel network-based psychophysiological interaction (nPPI) analysis to the reward task within the Human Connectome Project.
We first focused on responses evoked by DMN tasks and other networks involving the prefrontal cortex, including the executive control network (saliency network) and the left and right fronto-parietal networks.
Consistent with a multitude of previous studies, the DMN exhibited a relative decrease in activation over the course of the task, while the other networks exhibited a relative increase over the course of the task. Next, we used nPPI analyzes to assess whether these networks exhibited task-dependent changes in connectivity with other brain regions.
Strikingly, we found that reward experience enhances task-dependent connectivity between the DMN and the ventral striatum, a DMN-specific effect. Surprisingly, the strength of DMN-VS connectivity was correlated with openness-related personality characteristics.
Taken together, these results advance models of DMN by demonstrating how it contributes to other brain systems when performing tasks and how these contributions relate to individual differences.
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