Goal-congruent default network activity facilitates cognitive control

Abstract

Substantial neuroimaging evidence suggests that spontaneous engagement of the default network impairs performance on tasks requiring executive control. We investigated whether this impairment depends on the congruence between executive control demands and internal mentation. We hypothesized that activation of the default network might enhance performance on an executive control task if control processes engage long-term memory representations that are supported by the default network. Using fMRI, we scanned 36 healthy young adult humans on a novel two-back task requiring working memory for famous and anonymous faces. In this task, participants (1) matched anonymous faces interleaved with anonymous face, (2) matched anonymous faces interleaved with a famous face, or (3) matched a famous faces interleaved with an anonymous face. As predicted, we observed a facilitation effect when matching famous faces, compared with anonymous faces. We also observed greater activation of the default network during these famous face-matching trials. The results suggest that activation of the default network can contribute to task performance during an externally directed executive control task. Our findings provide evidence that successful activation of the default network in a contextually relevant manner facilitates goal-directed cognition.

Keywords: cognitive control; default mode network; fMRI; long-term memory; n-back; working memory.

Figure 1.

Faces n-back task structure and performance. A, The faces two-back consisted of a stream of stimuli including famous and anonymous faces. Three triplet conditions were embedded within the task: AAA, AFA, and FAF. In the bottom, performance for the AAA, AFA, and FAF triplet matching for (B) accuracy, and (C) RT for correct trials.

Figure 2.

Sustained and transient brain activity during the faces n-back task. A, Sustained block activity for the faces n-back task (warm colors) and fixation (cool colors). B, Transient activity during the first instance of viewing a famous (warm colors) versus anonymous (cool colors) face. C, Transient activity during the triplets for famous face matching (warm colors) and anonymous face matching (cool colors) conditions.

Figure 3.

Matching anonymous and famous faces. A, Composite brain activity scores for the anonymous face-matching triplets (AAA/AFA) and famous face-matching triplets (FAF; see Fig. 2C for corresponding brain activity map). B, Composite brain activity scores in the median RT split analysis of the anonymous and famous face-matching triplets. For both (A) and (B), anonymous face-matching conditions covary together and are dissociated from famous face-matching conditions. No differences were observed within condition by RT. Confidence intervals calculated from the bootstrap resampling. C, Brain activity for the median RT split analysis during the triplets for famous face-matching (warm colors) and anonymous face-matching (cool colors) conditions.