More expertise for a better perspective: Task and strategy-driven adaptive neurofunctional reorganization for word production in high-performing older adults

Abstract

The suggestion that neurofunctional reorganization may contribute to preserved language abilities is still emerging in aging studies. Some of these abilities, such as verbal fluency (VF), are not unitary but instead rely on different strategic processes that are differentially changed with age. Younger (n = 13) and older adults (n = 13) carried out an overt self-paced semantic and orthographic VF tasks within mixed fMRI design. Our results suggest that patterns of brain activation sustaining equivalent performances could be underpinned by different strategies facing brain changes during healthy aging. These main findings suggest that temporally mediated semantic clustering and frontally mediated orthographic switching were driven by evolutive neurofunctional resources in high-performing older adults. These age-related activation changes can appear to be compatible with the idea that unique neural patterns expressing distinctive cognitive strategies are necessary to support older adults' performance on VF tasks.

Neural Correlates of Verb Fluency Performance in Cognitively Healthy Older Adults and Individuals With Dementia: A Pilot fMRI Study

“…Therefore, in the current pilot study, we tested individuals with dementia and cognitively healthy older adults (without a diagnosis of dementia) not only to compare their brain activation patterns, but also to determine brain regions closely associated with verb fluency performance. It was hypothesized that individuals with dementia will show significant upregulation of frontal lobe areas given the increased burden of search strategies dealing with degraded semantic information and access (Melrose et al, 2009;Reilly et al, 2011;Beber et al, 2015;Methqal et al, 2019); this hypothesis is also consistent with prior work documenting that impairments in verb fluency are associated with frontal lobe lesions (Piatt et al, 1999;Davis et al, 2010;Beber and Chaves, 2014). Additionally, it was hypothesized that there will be subcortical and deep brain regions exhibiting significant correlations with verb fluency performance.…”

“…Also, bilateral frontal areas are reportedly a common ground brain network recruited during different types of verbal fluency tasks and word retrieval (e.g., fill-in-the-blank sentence completion) in healthy young adults (Li et al, 2017). The current findings in which individuals with dementia demonstrated upregulation of these frontal lobe areas may indicate (a) compensatory mechanisms utilized to generate as many words as possible in the face of decreased cognitive and linguistic resources, or (b) neural maladaptation or inefficiency, with frontal involvement being detrimental to verb fluency performance (Morcom and Henson, 2018;Methqal et al, 2019). Although we cannot distinguish between these two hypotheses in the current study, our findings suggest that despite higher bilateral frontal lobe activation among individuals with dementia, these participants still demonstrated poorer performance compared to cognitively healthy older adults, supporting the previous findings of Meinzer et al (2009Meinzer et al ( , 2012 and consistent with the CRUNCH (Compensation-Related Utilization of Neural Circuits Hypothesis; Reuter-Lorenz and Cappell, 2008) effects.…”

Cortical Networks Underpinning Compensation of Verbal Fluency in Normal Aging

“…2014 ; Marsolais et al. 2015 ; Methqal et al. 2019 ) comprise a cortical network that is associated with performance in PF in our reference group of younger participants (32–58 years).…”

Automatic Scoring of Semantic Fluency

“…We first conduct linear regression analyses that use measurements from both the VSM and the Backlink model as predictors of age, and then use logistic regression analyses to examine the sensitivity of the models to different age groups (younger vs. older). As well as the switch counts, we also include cluster sizes as predictors following the literature (Troyer et al, 1997; Methqal et al, 2019) (see Table 8 for the full list).…”