Aging effects on working memory: Fronto-parietal network involvement on tasks involving speech stimuli

Abstract

Healthy aging is marked by changes in a variety of interconnected brain areas involved in cognition and memory function. The present study focused on brain networks involved in memory recall following mental manipulation of speech items, in a task known as the backward repeat task (BRT). Effects of aging on brain activation were examined in four groups of adult participants ranging in age between 20 and 65 years using functional MRI (fMRI), to test whether aging is associated with functional network activity changes on tasks involving working memory of speech stimuli. Behavioral results reveal that performance accuracy declines with increasing age. fMRI results show that all groups of participants recruited the same brain areas during BRT. However, they differ in number of activated voxels, t-values and LI (laterality index). Results also reveal that older participants recruited the cerebellum and precuneus bilaterally to a greater extent than younger participants. The bilateral recruitment of cerebellum and precuneus in older participants was coupled with a decrease of brain activity in frontal areas. Based on these findings we suggest that, whereas all four groups of participants used the same areas in processing, the engagement and recruitment of the involved areas were different with increasing age. Findings are discussed in the context of supporting evidence related to reorganization of neural function with declining cognitive processes.