Abstract
The default mode network (DMN) is engaged in a variety of cognitive settings, including social, semantic, temporal, spatial, and self-related tasks. Andrews-Hanna et al. (2010; Andrews-Hanna 2012) proposed that the DMN consists of three distinct functional–anatomical subsystems—a dorsal medial prefrontal cortex (dMPFC) subsystem that supports social cognition; a medial temporal lobe (MTL) subsystem that contributes to memory-based scene construction; and a set of midline core hubs that are especially involved in processing self-referential information. We examined activity in the DMN subsystems during six different tasks: 1) theory of mind, 2) moral dilemmas, 3) autobiographical memory, 4) spatial navigation, 5) self/other adjective judgment, and 6) a rest condition. At a broad level, we observed similar whole-brain activity maps for the six contrasts, and some response to every contrast in each of the three subsystems. In more detail, both univariate analysis and multivariate activity patterns showed partial functional separation, especially between dMPFC and MTL subsystems, though with less support for common activity across the midline core. Integrating social, spatial, self-related, and other aspects of a cognitive situation or episode, multiple components of the DMN may work closely together to provide the broad context for current mental activity.
Highlights
The default mode network (DMN) was originally discovered as a collection of medial prefrontal, lateral temporal, lateral parietal, and posterior medial cortical regions that reliably exhibit enhanced activity during passive rest compared to simple, externally oriented tasks (Shulman et al 1997; Raichle et al 2001). Raichle et al (2001) postulated that the DMN is involved in cognitive states that are suspended during many attentionally demanding tasks
Andrews-Hanna et al (2010; Andrews-Hanna 2012) proposed that the DMN consists of three distinct functional–anatomical subsystems—a dorsal medial prefrontal cortex subsystem that supports social cognition; a medial temporal lobe (MTL) subsystem that contributes to memory-based scene construction; and a set of midline core hubs that are especially involved in processing self-referential information
Across this combination of tasks and analysis methods, we found a degree of functional separation between DMN regions, largely consistent with the Andrews-Hanna (2010) dorsal medial prefrontal cortex (dMPFC) and MTL subsystems, though less so with their concept of the midline core
Summary
The default mode network (DMN) was originally discovered as a collection of medial prefrontal, lateral temporal, lateral parietal, and posterior medial cortical regions that reliably exhibit enhanced activity during passive rest compared to simple, externally oriented tasks (Shulman et al 1997; Raichle et al 2001). Raichle et al (2001) postulated that the DMN is involved in cognitive states that are suspended during many attentionally demanding tasks. A large body of literature has provided evidence that the DMN supports several aspects of spontaneous and deliberate self-generated thought that transcend the immediate sensory environment (Christoff et al 2004, 2009; Buckner et al 2008; Andrews-Hanna 2012; Andrews-Hanna, Smallwood, et al 2014b) Complementing this strong activity during rest, subsequent work has shown DMN activity across a variety of high-level tasks, including social (Greene and Haidt 2002; Mars et al 2012; Molenberghs et al 2016), semantic (Binder et al 2009; Humphreys and Lambon Ralph 2017), episodic (Ranganath and Ritchey 2012; Rugg and Vilberg 2013), and self-referential (Kelley et al 2002; Chiou et al 2019) cognition. There could be reduced processing of contextual features during focused attention on the details of an external task, but enhancement during spontaneous, self-generated cognition at rest
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