Unilateral disruptions in the default network with aging in native space

Abstract

BackgroundDisruption of the default-mode network (DMN) in healthy elders has been reported in many studies.MethodsIn a group of 51 participants (25 young, 26 elder) we examined DMN connectivity in subjects' native space. In the native space method, subject-specific regional masks (obtained independently for each subject) are used to extract regional fMRI times series. This approach substitutes the spatial normalization and subsequent smoothing used in prevailing methods, affords more accurate spatial localization, and provides the power to examine connectivity separately in the two hemispheres instead of averaging regions across hemispheres.ResultsThe native space method yielded new findings which were not detectable by the prevailing methods. The most reliable and robust disruption in elders' DMN connectivity were found between supramarginal gyrus and superior-frontal cortex in the right hemisphere only. The mean correlation between these two regions in young participants was about 0.5, and dropped significantly to 0.04 in elders (P = 2.1 × 10−5). In addition, the magnitude of functional connectivity between these regions in the right hemisphere correlated with memory (P = 0.05) and general fluid ability (P = 0.01) in elder participants and with speed of processing in young participants (P = 0.008). These relationships were not observed in the left hemisphere.ConclusionThese findings suggest that analysis of DMN connectivity in subjects' native space can improve localization and power and that it is important to examine connectivity separately in each hemisphere.

Alteration of the Intra- and Cross- Hemisphere Posterior Default Mode Network in Frontal Lobe Glioma Patients

“…First, intra-group analysis of the controls indicated that the significant difference observed between intra- and cross-hemispheric FC strength was consistent with previous studies3031. However, in the patient group, this difference was not detected.…”

Multimodal fusion of structural and functional brain imaging in depression using linked independent component analysis

“…Additionally, advancing age was negatively associated with IC2, indicating decreased FA globally, but also increased RD and to some extent MD, consistent with the aging literature (Davis et al, ; Sexton et al, ; Westlye et al, ). Higher age was associated with IC5, reflecting age‐related decreases in DMN amplitude, in line with previous research (Damoiseaux et al, ; Mevel et al, ; Mowinckel, Espeseth, & Westlye, ; Razlighi et al, ; Vidal‐Piñeiro et al, ). We observed high prediction accuracy for age in the machine learning approach.…”

Functional segregation loss over time is moderated by APOE genotype in healthy elderly

“…Given the moderate reliability (Supporting Information, Table S2), these functional connectivity measures may have limited sensitivity to detect cognition‐ or genetic‐related associations. Future studies need to improve sensitivity by enhancing longitudinal sampling and considering the complex relationships between more regionally defined functional connectivity (Razlighi et al, ). Third, our study focused on linear functional brain changes.…”