Age-Dependent Contribution of Domain-General Networks to Semantic Cognition

Abstract

Aging is characterized by a decline of cognitive control. In semantic cognition, this leads to the paradox that older adults usually show poorer task performance than young adults despite their greater semantic knowledge. So far, the underlying neural changes of these behavioral differences are poorly understood. In the current neuroimaging study, we investigated the interaction of domain-specific and domain-general networks during verbal semantic fluency in young and older adults. Across age groups, task processing was characterized by a strong positive integration within the multiple-demand as well as between the multiple-demand and the default mode network during semantic fluency. However, the behavioral relevance of strengthened connectivity differed between groups: While within-network functional connectivity in both networks predicted greater efficiency in semantic fluency in young adults, it was associated with slower performance in older adults. Moreover, only young adults profited from connectivity between networks for their semantic memory performance. Our results suggest that the functional coupling of usually anticorrelated networks is critical for successful task processing, independent of age, when access to semantic memory is required. Furthermore, our findings lend novel support to the notion of reduced efficiency in the aging brain due to neural dedifferentiation in semantic cognition.

Age-related differences in the neural network interactions underlying the predictability gain

“…This reflects higher sensitivity towards intelligibility in highly predictable speech selectively in older adults and suggests a potential beneficial effect of inhibition within the cingulo-opercular network when semantic context can be used to predict upcoming speech. Further evidence supporting this notion comes from a recent study demonstrating that increased connectivity within domain-general networks was associated with less efficient behavioural performance in a semantic task in older adults (Martin, Saur, & Hartwigsen, 2021). Importantly, the opposite pattern was observed for young adults, which converges with our finding of increased connectivity within the cingulo-opercular network in young adults.…”

The role of the angular gyrus in semantic cognition – A synthesis of five functional neuroimaging studies

“…We combined the fMRI data of 5 different studies on semantic processing from our laboratory (Kuhnke et al 2020b; Chapman and Hartwigsen 2021; Graessner et al 2021; Turker et al 2021; Martin et al 2021). Table 1 presents an overview of all studies.…”

“…Study D: Martin et al (2021) In the study by Martin et al (2021), 30 healthy adults performed an overt semantic fluency task on easy categories (e.g., colors, animals) and difficult categories (e.g., metals, flowers), as well as an overt counting task with easy (forward) and difficult (backward) conditions.…”

“…The AG generally showed relatively higher activity for semantic than non-semantic conditions. The only exception was study D (Martin et al 2021), where a semantic fluency task induced relatively lower activity than a counting task. Several possibilities may explain this result:…”

“…To address these issues, we combined and re-analyzed the fMRI data of 5 different studies on semantic processing from our laboratory (Kuhnke et al 2020b; Chapman and Hartwigsen 2021; Graessner et al 2021; Turker et al 2021; Martin et al 2021). For each study, we investigated the response profiles of the same anatomical regions-of-interest (ROIs) for left and right PGa and PGp.…”