Search Abstracts | Symposia | Slide Sessions | Poster Sessions
Resting-state functional connectivity between semantic and language networks in typical aging
Poster Session C, Saturday, September 13, 11:00 am - 12:30 pm, Field House
Zuzanna Osiecka1, Soodeh Moallemian1, Miray Budak1, Mark A. Gluck1, William W. Graves1; 1Rutgers University–Newark
Deficits in specific aspects of language often impact communication among older adults. Typical declines in working memory do not explain impairments in language function, as some features, such as vocabulary and semantic knowledge, are not only preserved in old age, but improve throughout adulthood. While the semantic system remains well-preserved, the phonological and orthographic systems decline. Functional neuroimaging studies have identified a semantic network, specialized for the storage and retrieval of semantic knowledge, and a more recently recognized language network comprising brain areas activated for both language comprehension and production. However, how interactions between these two networks change with age remains unclear. As the older adult population continues to grow, identifying neural patterns linked to language ability can help clarify this gap in the literature. Forty cognitively unimpaired older adults (mean age = 69.8, SD = 6.0, range = 61-87; 33 women, 7 men) were drawn from an ongoing study at Rutgers University–Newark. Participants underwent structural and resting-state functional MRI and completed the Controlled Oral Word Association Test (COWAT) as a measure of semantic fluency. Neuroimaging data were preprocessed using fMRIPrep 24.1.1 with its standard pipeline. Using AFNI (Analysis of Functional NeuroImages) software, afni_proc.py was applied to account for regressors of no interest. Binary masks for spatially defining the semantic and language networks were taken from previous studies, applied in MNI space, and used as seeds for calculating functional connectivity with regions outside the networks. Contrast maps were generated to compare areas of connectivity between the semantic and language networks. A 5 mm Gaussian smoothing kernel was applied before conducting group level analyses with 3dttest++ to examine how this contrast varied as a function of age, level of education, and semantic fluency. Results were corrected for multiple comparisons using cluster-based thresholding (voxel p < 0.001, mapwise corrected to p < 0.05). Areas were identified according to the Julich Brain atlas. Analyzing change in network connectivity with age, the language network showed stronger connectivity in the right angular gyrus (area PG); however, the semantic network only showed trending negative connectivity in the same region (p = .07). A significant difference in connectivity was observed at the interface between the semantic and language networks modulated by age and localized primarily to the right PG (Z = -4.21) adjacent to the supramarginal gyrus (area PF). Although connectivity between these networks was not significantly modulated by semantic fluency, this was not entirely unexpected as our sample was cognitively unimpaired (mean COWAT = 17.3, SD = 3.1). Our findings reveal that connectivity at the interface between the semantic and language networks is modulated by age. Though our sample consisted of solely older adults, the variability in age was sufficient to detect differences in connectivity patterns between semantic and language areas. Considered separately, the language network was significantly modulated by age, while the semantic network was not. This suggests that language functions are more vulnerable to age-related changes than semantic functions, and underscores the important role of age in the interactions between semantic and language networks.
Topic Areas: Meaning: Lexical Semantics, Control, Selection, and Executive Processes