Reduced functional coupling in the default-mode network during self-referential processing

Abstract

Activity within the default-mode network (DMN) is thought to be related to self-referential processing, such as thinking about one's preferences or personality traits. Although the DMN is generally considered to function as a network, evidence is starting to accumulate that suggests that areas of the DMN are each specialized for different subfunctions of self-referential processing. Here, we address the issue of functional specialization by investigating changes in coupling between areas of the DMN during self-referential processing. To this aim, brain activity was assessed during a task in which subjects had to indicate whether a trait adjective described their own personality (self-referential, Self condition), that of another person (other-referential, Other condition), or whether the trait was socially desirable (nonreferential, Control condition). To exclude confounding effects of cardiorespiratory processes on activity and functional coupling, we corrected the fMRI signal for these effects. Activity within areas of the DMN was found to be modulated by self-referential processing. More specifically, during the Self condition compared to the Other and Control condition, activity within the dorsal medial prefrontal cortex, ventral medial prefrontal cortex, and posterior cingulate cortex was increased. Moreover, coupling between areas of the DMN was reduced during the Self condition compared to the Other and Control condition, while coupling between regions of the DMN and regions outside the network was increased. As such, these results provide an indication for functional specialization within the DMN and support the notion that each area of the DMN is involved in different subfunctions of self-referential processing.

Figure 1

Self‐reflection task. The stimulus duration and interstimulus interval (ISI) duration were dependent on the reaction time; the fixation cross appeared as soon as the subject responded for the remaining trial time.

Figure 2

Whole brain activation overlaid on the mean anatomical image. (A) Significant activation during the Self condition compared to the Control condition. (B) Significant activation during the Self condition compared to the Other condition. Cluster‐defining threshold of P < 0.001 with a P < 0.05 FWE‐corrected cluster size of 18 voxels. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Figure 3

Areas showing significant psychophysiological interactions overlaid on the mean anatomical image. Areas showing decreased (blue) or increased (red) coupling with (A) the dMPFC, (B) the vMPFC, (C) the PCC during the Self condition compared to the Control condition, and with (D) the PCC during the Self condition compared to the Other condition. Seed regions are depicted in green. Cluster‐defining threshold of P < 0.001 with a P < 0.05 FWE‐corrected cluster size of 23 voxels. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]