Age-related increases in right frontal cortex activation are a common finding in the neuroimaging literature. However, neurocognitive factors contributing to right frontal over-recruitment remain poorly understood. Here we investigated the influence of age-related reaction time (RT) slowing and white matter (WM) microstructure reductions as potential explanatory factors for age-related increases in right frontal activation during task switching. Groups of younger (N=. 32) and older (N=. 33) participants completed a task switching paradigm while functional magnetic resonance imaging (fMRI) was performed, and rested while diffusion tensor imaging (DTI) was performed. Two right frontal regions of interest (ROIs), the dorsolateral prefrontal cortex (DLPFC) and insula, were selected for further analyses from a common network of regions recruited by both age groups during task switching. Results demonstrated age-related activation increases in both ROIs. In addition, the older adult group showed longer RT and decreased fractional anisotropy in regions of the corpus callosum with direct connections to the fMRI ROIs. Subsequent mediation analyses indicated that age-related increases in right insula activation were mediated by RT slowing and age-related increases in right DLPFC activation were mediated by WM microstructure. Our results suggest that age-related RT slowing and WM microstructure declines contribute to age-related increases in right frontal activation during cognitive task performance.
|Number of pages
|Published - 2014
Bibliographical noteFunding Information:
This study was supported by the National Institute on Aging of the National Institutes of Health under award number R01AG033036 and the National Science Foundation under award number BCS 0814302 . The content is solely the responsibility of the authors and does not necessarily represent the official views of these granting agencies. We thank our study volunteers for their participation in this research.
- Neural efficiency
- Task switching
ASJC Scopus subject areas
- Neuroscience (all)