Working memory (WM) entails maintenance and manipulation of information in the absence of sensory input. This study investigated the trajectories and neural basis of these component processes of WM functions in aging. Longitudinal human functional magnetic resonance imaging (fMRI) data are presented from 136 elderly individuals (55-80 years) who were scanned at baseline and again 4 years later. We obtained evidence that age-related changes in parietal and frontal components of the frontal-parietal WM core network are dissociable in terms of their role in maintenance of perceptual representations and further manipulation of this information, respectively. Individual difference analyses in performance subgroups showed that only prefrontal changes in fMRI activation were accompanied by changes in performance, but parietal brain activity was related to study drop-out. We discuss the results in terms of possible neurobiological causes underlying separable aging-related declines in inferior parietal cortex and lateral prefrontal cortex that differentially affect WM functions.
Significance Statement Working memory (WM) describes the ability to maintain and manipulate information over brief periods of time after the information is no longer present in the environment, which is important for human goal-oriented behavior, reasoning and decision-making. Age-related changes in WM functions and their neural basis are not fully understood, largely because of a scarcity of longitudinal data. Using functional magnetic resonance imaging (fMRI), this study of 136 older adults provides novel evidence for a decline of WM functions and underlying brain activity over a 4-year interval. We suggest the existence of two separable, age-related changes in brain function that differentially affect WM functions.
Authors report no conflict of interest.
This work was supported by a grant from the Knut and Alice Wallenberg Foundation, and a grant from the Söderberg’s Foundation to LN. AR was supported by a Marie Curie International Outgoing Fellowship from the European Commission.