Metabolic and structural connectivity within the default mode network relates to working memory performance in young healthy adults

Abstract

Studies of functional connectivity suggest that the default mode network (DMN) might be relevant for cognitive functions. Here, we examined metabolic and structural connectivity between major DMN nodes, the posterior cingulate (PCC) and medial prefrontal cortex (MPFC), in relation to normal working memory (WM). Metabolic connectivity, a correlation between FDG uptake in PCC and MPFC, was examined in groups of subjects with (relative to median) low (n=18) and high (n=17) performance on digit span backward test as an index of verbal WM. In addition, fiber tractography based on PCC and MPFC nodes as way points was performed in a subset of subjects.FDG uptake in the DMN nodes did not differ between high and low performers. However, significantly (p=0.01) lower metabolic connectivity was found in the group of low performers.Furthermore, as compared to high performers, low performers showed lower density of the left superior cingulate bundle.Verbal WM performance is related to metabolic and structural connectivity within the DMN in young healthy adults. Metabolic connectivity as quantified with FDG-PET might be a sensitive marker of the normal variability in some cognitive functions.

Metabolic Connectivity as Index of Verbal Working Memory

“…This observation is consistent with a previously reported whole-brain voxel-wise analysis in the same groups. 10 …”

“…Recently, we found support for the functional role of the DMN, a network that is deactivated during attention-demanding tasks, in verbal WM. 10 Here, we focused on task-positive regions, i.e., regions that are activated by a verbal WM task. 9 Under such conditions, the two previously reported DMN clusters were not identified as part of the (in nature task-positive) network of six BAs.…”

“…To link to our previous work, 10 we included two original clusters from that study, the posterior cingulate and prefrontal regions, as additional nodes in the present SICE. To address the issue of specificity, we in a separate analysis included two regions of no interest, the vermis and crus of the cerebellum from the WFU PickAtlas.…”

Relation between patterns of intrinsic network connectivity, cognitive functioning, and symptom presentation in trauma‐exposed patients with major depressive disorder

“…In our sample, however, increased integration of the DMN with a core region of this network was related to better neuropsychological performance. Interestingly, studies in other populations, such as in patients with Parkinson's disease (Disbrow et al., 2014; Tessitore et al., 2012), healthy older adults (Ward et al., 2014), and healthy controls (Yakushev et al., 2013) have reported that greater connectivity within the DMN is associated with better performance on different memory tasks. Our results are also consistent with recent findings suggesting that among patients with depression, but not healthy controls, better performance on a delayed recall trial of list learning was predictive of greater connectivity between the parahippocampus and subcortical structures (Rao et al., 2016).…”

“…For example, connectivity within the DMN is positively associated with verbal working memory among healthy adults (Yakushev et al., 2013), and with memory performance (using a memory composite score) among older adults (Ward et al., 2014). Healthy controls also demonstrated an association between CEN connectivity and superior performance on Trails B, a measure of alternating attention (Seeley et al., 2007).…”