Abstract
IntroductionMultiple object tracking (MOT) is a powerful paradigm for measuring sustained attention. Although previous fMRI studies have delineated the brain activation patterns associated with tracking and documented reduced tracking performance in aging, age‐related effects on brain activation during MOT have not been characterized. In particular, it is unclear if the task‐related activation of different brain networks is correlated, and also if this coordination between activations within brain networks shows differential effects of age.MethodsWe obtained fMRI data during MOT at two load conditions from a group of younger (n = 25, mean age = 24.4 ± 5.1 years) and older (n = 21, mean age = 64.7 ± 7.4 years) healthy adults. Using a combination of voxel‐wise and independent component analysis, we investigated age‐related differences in the brain network activation. In order to explore to which degree activation of the various brain networks reflect unique and common mechanisms, we assessed the correlations between the brain networks' activations.ResultsBehavioral performance revealed an age‐related reduction in MOT accuracy. Voxel and brain network level analyses converged on decreased load‐dependent activations of the dorsal attention network (DAN) and decreased load‐dependent deactivations of the default mode networks (DMN) in the old group. Lastly, we found stronger correlations in the task‐related activations within DAN and within DMN components for younger adults, and stronger correlations between DAN and DMN components for older adults.ConclusionUsing MOT as means for measuring attentional performance, we have demonstrated an age‐related attentional decline. Network‐level analysis revealed age‐related alterations in network recruitment consisting of diminished activations of DAN and diminished deactivations of DMN in older relative to younger adults. We found stronger correlations within DMN and within DAN components for younger adults and stronger correlations between DAN and DMN components for older adults, indicating age‐related alterations in the coordinated network‐level activation during attentional processing.
Highlights
Multiple object tracking (MOT) is a powerful paradigm for measuring sustained attention
An ANCOVA exploring whether differences in performance on the neuropsychological tests correlated with activation levels in the selected dorsal attention network (DAN) and default mode networks (DMN) components revealed no significant correlation between Wechsler Abbreviated Scale of Intelligence (WASI) matrix reasoning and beta coefficients for either group
Using a combination of fMRI-based voxel and multivariate analyses across a range of large-scale brain networks obtained during multiple object tracking, we have demonstrated age-related differences in tracking performance and associated brain network recruitment, in particular related to task-related activation and deactivations of the DAN and DMN, respectively
Summary
Attention entails a differential allocation of cognitive resources toward task-relevant information at the expense of that deemed less relevant. We investigated age differences in the task-related activations across a range of brain networks during multiple object tracking (MOT) (Pylyshyn & Storm, 1988). 3. Based on the concept that cognition is enabled by the temporal synchronization of different brain networks and in line with the notion of dedifferentiation in cognitive aging (Andrews-Hanna et al, 2007; Baltes & Lindenberger, 1997; Chan, Park, Savalia, Petersen, & Wig, 2014; Lindenberger, 2014), we anticipated that age effects would be revealed in a differential pattern of correlations in levels of task-related activations between the two age groups. We anticipate stronger correlation in levels of co-activation between task-related components, within the DAN and DMN for the younger group compared to the older group
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