The maturing architecture of the brain's default network

TLDR

The brain’s default network, a set of regions that deactivate during goal‑oriented tasks, has attracted interest and debate, with early work linking it to self‑referential and introspective processes and later studies associating it with internal narrative, autobiographical self, stimulus‑independent thought, mentalizing, and self‑projection, yet most research has focused only on mature adults. The study aimed to gain insight into the default network’s functioning by examining its developmental trajectory. Resting‑state functional connectivity MRI was employed to map the default network’s maturation across childhood. Results showed that at ages 7–9 the default regions are only sparsely connected, but with age they progressively integrate into a cohesive, interconnected network.

Abstract

In recent years, the brain's “default network,” a set of regions characterized by decreased neural activity during goal-oriented tasks, has generated a significant amount of interest, as well as controversy. Much of the discussion has focused on the relationship of these regions to a “default mode” of brain function. In early studies, investigators suggested that, the brain's default mode supports “self-referential” or “introspective” mental activity. Subsequently, regions of the default network have been more specifically related to the “internal narrative,” the “autobiographical self,” “stimulus independent thought,” “mentalizing,” and most recently “self-projection.” However, the extant literature on the function of the default network is limited to adults, i.e., after the system has reached maturity. We hypothesized that further insight into the network's functioning could be achieved by characterizing its development. In the current study, we used resting-state functional connectivity MRI (rs-fcMRI) to characterize the development of the brain's default network. We found that the default regions are only sparsely functionally connected at early school age (7–9 years old); over development, these regions integrate into a cohesive, interconnected network.