Tasks activating the default mode network map multiple functional systems

The default mode network (DMN), traditionally viewed as a single network active during rest and deactivated during tasks, may actually consist of multiple subsystems supporting a broader range of functions than previously thought. This meta-analysis of neuroimaging studies found that DMN activation patterns can be arranged along a continuous gradient from core midline regions linked to internal mental processes to lateral cortices involved in external tasks such as reward, semantic processing, and emotion. Importantly, many task-related activation maps differed from the canonical resting-state DMN, sometimes overlapping only in peripheral nodes and including regions like the insula. These results suggest that the distinction between intrinsic and extrinsic brain functions is better conceptualized as a continuum rather than a strict dichotomy.

Study at a glance

Abstract

Recent developments in network neuroscience suggest reconsidering what we thought we knew about the default mode network (DMN). Although this network has always been seen as unitary and associated with the resting state, a new deconstructive line of research is pointing out that the DMN could be divided into multiple subsystems supporting different functions. By now, it is well known that the DMN is not only deactivated by tasks, but also involved in affective, mnestic, and social paradigms, among others. Nonetheless, it is starting to become clear that the array of activities in which it is involved, might also be extended to more extrinsic functions. The present meta-analytic study is meant to push this boundary a bit further. The BrainMap database was searched for all experimental paradigms activating the DMN, and their activation likelihood estimation maps were then computed. An additional map of task-induced deactivations was also created. A multidimensional scaling indicated that such maps could be arranged along an anatomo-psychological gradient, which goes from midline core activations, associated with the most internal functions, to that of lateral cortices, involved in more external tasks. Further multivariate investigations suggested that such extrinsic mode is especially related to reward, semantic, and emotional functions. However, an important finding was that the various activation maps were often different from the canonical representation of the resting-state DMN, sometimes overlapping with it only in some peripheral nodes, and including external regions such as the insula. Altogether, our findings suggest that the intrinsic–extrinsic opposition may be better understood in the form of a continuous scale, rather than a dichotomy.