Performance level modulates adult age differences in brain activation during spatial working memory

Abstract

Working memory (WM) shows pronounced age-related decline. Functional magnetic resonance imaging (fMRI) studies have revealed age differences in task-related brain activation. Evidence based primarily on episodic memory studies suggests that brain activation patterns can be modulated by task difficulty in both younger and older adults. In most fMRI aging studies on WM, however, performance level has not been considered, so that age differences in activation patterns are confounded with age differences in performance level. Here, we address this issue by comparing younger and older low and high performers in an eventrelated fMRI study. Thirty younger (20 -30 years) and 30 older (60 -70 years) healthy adults were tested with a spatial WM task with three load levels. A region-of-interest analysis revealed marked differences in the activation patterns between high and low performers in both age groups. Critically, among the older adults, a more ''youth-like'' load-dependent modulation of the blood oxygen level-dependent signal was associated with higher levels of spatial WM performance. These findings underscore the need of taking performance level into account when studying changes in functional brain activation patterns from early to late adulthood.aging ͉ fMRI ͉ premotor cortex ͉ performance load

Deficit in switching between functional brain networks underlies the impact of multitasking on working memory in older adults

“…Evidence for the behavioral relevance of this finding was generated by a whole-brain analysis, which showed that in both younger and older adults, MFG-PPA connectivity in delay 2 correlated with subsequent WM accuracy (both P < 0.05, corrected for multiple comparisons) (4). These findings suggest that those participants who were best able to reactivate the stored memoranda postinterruption (via restoration of MFG-PPA connectivity) performed with the highest WM accuracy, highlighting the importance of assessing individual differences even in age-comparative studies (21). However, as a group, older participants were unable to attain levels achieved by the younger participants, which suggests an age-related reactivation deficit (support for hypothesis 2).…”

Hippocampal–Dorsolateral Prefrontal Coupling as a Species-Conserved Cognitive Mechanism: A Human Translational Imaging Study

“…This indicates that HC-DLPFC coupling may be a systems-level correlate specific to spatial WM performance that can be found in several species. Impaired information processing during WM has been found to be a core cognitive deficit in schizophrenia (Barch and Ceaser, 2012) and has also been observed during normal aging (Nagel et al, 2009). Virtual navigation paradigms have already been successfully used in aged subjects and in clinical populations (Konishi et al, 2013;Sneider et al, 2013;Spieker et al, 2012;Yuan et al, 2014).…”

Working Memory: Maintenance, Updating, and the Realization of Intentions

“…This prediction is supported by the results from human lesion studies showing that frontal lesions have weak or no negative effects on simple workingmemory maintenance (e.g., Volle et al 2008;Barbey et al 2013). In contrast, frontal lesions, notably in the dorsolateral cortex, have marked impact on working-memory manipulation operations, and functional imaging studies have shown elevated dorsolateral prefrontal activity as a function of the complexity of workingmemory operations (e.g., Nagel et al 2009;Nyberg et al 2009b). It should be stressed that increased complexity can be instantiated by using tasks that require that some operation is performed on the information that is maintained in working memory (e.g., letter-number sequencing or digit-span backward) or by increasing the number of items that have to be maintained (as in Sternberg type of tasks).…”