Poster #15 - Default Mode Network Subsystems Display Distinct Maturational Trajectories

• In Event: 3-206 - Poster Session 13
  In Poster Session: PS 13 Section - Biological Processes: Neuroscience and Genetics

Integrative Statement

Over the past two decades, understanding of the brain’s intrinsic organization has grown rapidly. It is now widely accepted that the brain is composed of a series of distinct networks, each serving a specific functional role. The default mode network (DMN) is one of these primary networks (Yeo et al., 2011) and has been shown to facilitate higher-order internal cognitive activities such as self-referential thinking, autobiographical memory recall, social cognition, and future simulation (Buckner, 2008). This network, comprising parts of the medial and lateral temporal lobe, the posterior cingulate cortex (PCC), the inferior parietal lobe (IPL), the medial prefrontal cortex (mPFC), as well as a portion of the ventral lateral prefrontal cortex (vlPFC), displays protracted maturation, with adult-like resting-state functional connectivity not observed until early adulthood (Fair, 2008). Previous work on DMN development has been limited to specific age ranges: 3-5 (Xiao, 2015), 7-9 (Fair, 2008), and 10-13 (Sherman et al., 2014). No prior study has evaluated DMN development across childhood and adulthood or examined maturation of the three distinct DMN subsystems, identified by Yeo et al. in 2011 (see Figure 1). In the present study, we examined age-related variation in resting-state functional connectivity within the DMN in general, as well as the three DMN subsystems, using fMRI resting-state scans of 304 participants (ages 3-21) from the Pediatric Imaging, Neurocognition and Genetics publicly available dataset. We estimated linear, logarithmic, quadratic and cubic trajectories of maturation using age as a continuous variable. Functional connectivity within the whole DMN increased logarithmically with age (b = 0.030, p=0.041), while the three subsystems each displayed distinct patterns of age-related change in connectivity across development. The largest subnetwork (A), known for its involvement in internally oriented cognition (Christoff, 2016), followed a similar logarithmic trajectory (b = 0.076, p=0.0055) to the overall DMN, with increases in functional connectivity occurring most rapidly in early childhood and slowing in early adolescence. The most posterior subsystem (C), involved in memory (Christoff, 2016), did not exhibit age-related change (b = -0.0014, p=0.53), suggesting that this subnetwork maturates early on in the first few years of life with little change thereafter. The third and least well understood subnetwork (B) displayed a strong linear trajectory, with increasing connectivity continuing into early adulthood (b = 0.01, p<0.00001). The areas that compose subnetwork B are all associated with some form of social information processing—from biological motion and face processing (superior temporal sulcus) to semantic language processing (left angular gyrus) and theory of mind (dorsalmedial PFC). The finding that this DMN subnetwork continues to mature into early adulthood, while the other two subnetworks mature earlier in childhood, has implications for our understanding of the role of this DMN subsystem in social information processing, and the significant changes in social processing that occur across development. This finding also has broader implications for our current account of DMN function, as social information processing is not currently considered to be a central function of the DMN (Buckner, 2008; Christoff, 2016).

Authors

• Nessa Cell Bryce, Harvard University
  Presenting Author

• Katie McLaughlin, Harvard University
  Non-Presenting Author