Summary: The study shows how reward improves connectivity between the ventral striatum and the default mode network and affects behavior.

Source: Kessler Foundation

Researchers report findings that increase our understanding of how human behavior may be shaped by the default mode network, specific brain regions associated with rest and activity states.

The default mode network (DMN), which includes 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 inwardly directed thought and decreases during externally directed tasks that require attention.

Despite evidence for a role for the DMN in shaping behavior, little is known about how task-related changes in the DMN affect its connectivity with other brain regions. For example, although some observations indicate indirect connections between the DMN and striatum, it remains unclear how the DMN and striatum interact during tasks.

To further explore the functions of the DMN, Dr. Dobrikakova and Smith applied a novel analysis of reward function using behavioral and neuroimaging data from 495 individuals selected in the Human ConnectCom project.

The goals of this network-based analysis of psycho-physiological interactions are twofold, said Dr. Dobrikakova, senior research scientist at the Foundation’s Traumatic Brain Injury Research Center.

“First, to test the effects of reward on the relationship between the DMN and stroke; second, to determine whether such a relationship is associated with behavioral and personality traits related to reward processing.”

Consistent with other studies, they observed decreased DMN activation during the task and relative activation of other networks.

This shows the brain
Studies show that DMN activity increases during inwardly directed thought and decreases during externally directed tasks that require attention. The image is in the public domain.

“Specifically, we found that reward experience improved the connection between the DMN and the ventral striatum,” reports Dr. Dobrykakova, “an effect specific to the DMN. We were also surprised that the strength of this connection was associated with openness behaviors,” she added.

A greater understanding of the functioning of the healthy brain will have implications for future research and care for individuals with neuropsychiatric syndromes. “Improving our understanding of how the DMN interacts with other brain networks has the potential to aid clinical research to provide better treatments for common syndromes such as depression, substance abuse, and schizophrenia.”

Financial support This study was supported by a grant from the National Institutes of Health. R21-MH113917 (DVS), R03-DA046733 (DVS), RF1-AG067011 (DVS), R01-NS121107 (Ed.)

So reward and behavioral neuroscience research news

Author: Carolann Murphy
Source: Kessler Foundation
Contact: Carolann Murphy – Kessler Foundation
Image: The image is in the public domain.

Preliminary study: Open Access.
Reward improves connectivity between the ventral striatum and the default mode networkBy Ekaterina Dobryakova et al. Neurological imaging


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This shows the brain

Reward improves connectivity between the ventral striatum and the default mode network

The default mode network (DMN) is theorized to be involved in a variety of social, cognitive, and affective functions. However, previous accounts have not considered how the DMN contributes to other brain regions as a psychological context, thus leaving our understanding of DMN function incomplete.

We addressed this gap by applying a novel network-based psychophysiological interaction (nPPI) analysis to the reward function in the Human Connectum project.

We first focused on task-evoked responses in other networks involving the DMN and prefrontal cortex, including the executive control network (the salience network) and the left and right frontoparietal networks.

Consistent with a host of prior studies, the DMN showed a relative decrease in activation during the task, while the other networks showed a relative increase during the task. Next, we used nPPI analyzes to assess whether these networks exhibited task-dependent changes in connectivity with other brain regions.

Intriguingly, we found that reward experience enhances functional connectivity between the DMN and the ventral striatum, with effects specific to the DMN. Surprisingly, the strength of the DMN-VS connection was related to openness characteristics.

Taken together, these results advance models of the DMN by showing how the DMN contributes to other brain systems during task performance and how those contributions relate to individual differences.

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