Abstract :
[en] 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).
DMN was captured using independent component analysis of [18F]fluorodeoxyglucose
positron emission tomography (FDG-PET) data from 35 young healthy adults (27.1±5.1 years).
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.
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