Default-mode and task-positive network activity in major depressive disorder: implications for adaptive and maladaptive rumination

Abstract

Background: Major depressive disorder (MDD) has been associated reliably with ruminative responding; this kind of responding is composed of both maladaptive and adaptive components. Levels of activity in the default-mode network (DMN) relative to the task-positive network (TPN), as well as activity in structures that influence DMN and TPN functioning, may represent important neural substrates of maladaptive and adaptive rumination in MDD.

Methods: We used a unique metric to estimate DMN dominance over TPN from blood oxygenation level-dependent data collected during eyes-closed rest in 17 currently depressed and 17 never-disordered adults. We calculated correlations between this metric of DMN dominance over TPN and the depressive, brooding, and reflective subscales of the Ruminative Responses Scale, correcting for associations between these measures both with one another and with severity of depression. Finally, we estimated and compared across groups right fronto-insular cortex (RFIC) response during initiations of ascent in DMN and in TPN activity.

Results: In the MDD participants, increasing levels of DMN dominance were associated with higher levels of maladaptive, depressive rumination and lower levels of adaptive, reflective rumination. Moreover, our RFIC state-change analysis showed increased RFIC activation in the MDD participants at the onset of increases in TPN activity; conversely, healthy control participants exhibited increased RFIC response at the onset of increases in DMN activity.

Conclusions: These findings support a formulation in which the DMN undergirds representation of negative, self-referential information in depression, and the RFIC, when prompted by increased levels of DMN activity, initiates an adaptive engagement of the TPN.

Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

(A) Depiction using actual data of procedure for calculating DMN dominance over TPN. Examples of onset vectors (red) for DMN (B) and TPN (C) in the context of TPN (green) and DMN (blue) time-series data.

Figure 2

(A) Frequency maps for DMN (cool colors) and TPN (warm colors) derived from regression-defined masks for individuals in MDD and CTL groups. (B) Chi-square statistic map showing increased frequency of inclusion of right fronto-insular cortex in the TPN in the MDD group.

Figure 3

Negative correlation of DMN dominance with RRS-Reflection (top) and positive correlation of DMN dominance with RRS-Depression (bottom) in the MDD group.

Figure 4

(A) Region in right fronto-insular cortex of significant Network-by-Group interaction. (B) Impulse response functions from region in (A) as a function of Network onset and Group.