Aging effects on task-based activity and functional networks during semantic processing and rest
Poster No:
1192
Submission Type:
Abstract Submission
Authors:
Sandra Martin1, Philipp Kuhnke2, Curtiss Chapman3, Gesa Hartwigsen2
Institutions:
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Saxony, 2Leipzig University, Leipzig, Saxony, 3MPI CBS, Leipzig, Saxony
First Author:
Co-Author(s):
Introduction:
Semantic knowledge is essential for everyday human cognition, such as recognizing and using objects, or speaking and comprehending language. It is usually well preserved in healthy aging (Verhaeghen, 2003). However, semantic control processes, which guide semantic access and retrieval, decline with age (Hoffman, 2018). In light of the intact semantic knowledge system in healthy older adults, these changes have been attributed to declining cognitive control functions, which contribute to successful semantic processing when ambiguities need to be resolved or irrelevant information needs to be inhibited (DeDe and Knilans, 2016). A central question is how cognitive aging modulates the contribution of cognitive control networks to semantic processing in the brain. To date, most studies focused on large-scale network interactions at rest but little is known about the differences in network organization between rest and task states and their age-related modulation.To address these questions, the current neuroimaging study explored the interaction between neural resources of domain-specific semantic processing and domain-general cognitive control in healthy young and older adults. We applied univariate task-based analyses and characterized whole-brain functional connectivity profiles during rest and semantic processing to explore the relationship between these states and their modulation through age.
Methods:
41 older adults (M: 66, SD: 3.17 years) and 43 young adults (M: 28, SD: 4.3 years) performed semantic judgment tasks (taxonomic or thematic judgments) on pairs of images (e.g. monkey and banana) during fMRI. A scrambled mirror judgment task was included as a non-semantic control task. Task-related whole-brain activation was investigated via two-level GLM analyses in SPM12. Individual time series of 400 parcels (Schaefer, 2018) were extracted for rest and task runs separately, while performing rigorous denoising. Whole-brain functional connectivity estimates were calculated across the time series using Fisher's z coefficients. Matrices of rest and semantic processing were correlated within participants and an effect of age was explored via a t-test.
Results:
fMRI analyses showed activity in a left-lateralized fronto-temporo-parietal network for semantic > non-semantic tasks (Fig. 1). In both groups, activation peaks lay within networks of semantic control and domain-general cognitive control. Interaction analyses showed that young adults more strongly activated left frontal and parietal regions, and fusiform gyrus, for semantic vs. non-semantic tasks than older adults. Older adults, on the other hand, showed increased activity only in right-hemispheric frontal and parietal regions (Fig. 1 bottom). Whole-brain functional connectivity analyses revealed enhanced connectivity in young relative to older adults during rest and task states (Fig. 2A). Whole-brain connectivity matrices for rest and semantic processing were strongly interrelated within participants (Fig. 2B). However, these correlations did not show an effect of age (t(82) = 1.08, p = 0.28).
·Figure 1: Whole-brain activation for semantic vs non-semantic tasks. Upper figures show contrast Semantic > Non-semantic task in each age group. Lower figure shows age differences for the contrast Sem
·Figure 2: A) Average whole-brain correlation matrices per age group and state (semantic tasks, rest). B) Correlation between resting-state and task functional connectivity (FC) in each age group. OA:
Conclusions:
Our results demonstrate age-related changes in functional activity during semantic processing, driven by neural reorganization. While young adults showed increased activity in domain-specific semantic regions in left frontal, parietal, and inferior temporal lobes, older adults showed upregulation in right-hemispheric frontal and parietal regions, which have been associated with the frontoparietal control network. These results illustrate the increased involvement of domain-general resources in the aging brain to maintain goal-directed task processing when cognitive demands are high (Martin et al., 2022). We did not detect age differences in the synchronization of whole-brain networks during rest and task demonstrating a relatively stable functional network architecture across age groups.
Language:
Language Comprehension and Semantics 2
Lifespan Development:
Aging 1
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Connectivity (eg. functional, effective, structural)
Task-Independent and Resting-State Analysis
Keywords:
Aging
Cognition
FUNCTIONAL MRI
Language
Other - Semantic
1|2Indicates the priority used for review
Provide references using author date format
Hoffman, P. (2018). An individual differences approach to semantic cognition: Divergent effects of age on representation, retrieval and selection. Scientific Reports, 8(1), Article 1. https://doi.org/10.1038/s41598-018-26569-0
DeDe, G., & Knilans, J. (2016). Language comprehension in aging. In H. H. Wright (Ed.), Cognition, Language and Aging (pp. 107–133). John Benjamins Publishing Company. https://doi.org/10.1075/z.200.05ded
Schaefer, A., Kong, R., Gordon, E. M., Laumann, T. O., Zuo, X.-N., Holmes, A. J., Eickhoff, S. B., & Yeo, B. T. T. (2018). Local-Global Parcellation of the Human Cerebral Cortex from Intrinsic Functional Connectivity MRI. Cerebral Cortex (New York, N.Y.: 1991), 28(9), 3095–3114. https://doi.org/10.1093/cercor/bhx179
Martin, S., Saur, D., & Hartwigsen, G. (2022). Age-Dependent Contribution of Domain-General Networks to Semantic Cognition. Cerebral Cortex, 32(4), 870–890. https://doi.org/10.1093/cercor/bhab252