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Poster B39, Wednesday, November 8, 3:00 – 4:15 pm, Harborview and Loch Raven Ballrooms

State-dependant organization of the functional connectome with age

Perrine Ferré1, Yassine Benhajali1, Jason Steffener2, Yaakov Stern3, Yves Joanette1, Pierre Bellec1;1Centre de Recherche de l'Institut Universitaire de Montréal, 2University of Ottawa, 3Columbia University

According to the World Health Organization, the proportion of individuals over age 60 is expected to double by 2050. Considering this demographic shift, a better understanding of the mechanisms required to maintain cognitive health during normal and pathological aging is a crucial goal for contemporary health researchers. Most of our knowledge on brain functioning in aging focused on declining function (e.g.: working memory). Language processing related to vocabulary and semantic knowledge, which stand at the heart of inter-individual relationships, appear relatively well preserved and as such might shed light on reorganization processes at stake in healthy aging. In the past decade, connectivity measures in functional magnetic resonance imaging gained popularity to study age related brain mechanisms, established mainly on "task free" experimental design. But recent evidence points towards highly dynamic neurofunctional processing in aging, and it remains to be determined if age-related differences in functional connectivity are dependent on the cognitive context. From a sample of 300 adults ranging from 18 to 80 years old, we explored semantic and general cognitive performance in correlation with age, education and other socio-demographic characteristics. Then, 286 individuals reaching fMRI standards for quality assessment were tested systematically for whole brain connectivity to search for consistent differences as a function of age, performance or education during an fMRI session of resting-state and while performing three language tasks (antonyms, synonyms, picture naming).  Our results confirm a behavioral dissociation between semantic and neuropsychological performance: increasing age favors better performances for language tasks. Major discrepancies were further observed between task-evoked and resting state connectivity patterns. Mean functional connectivity shows a general tendency to decrease with age, but increases in synchronicity between core semantic-reading regions were revealed only during task performance. No interactions were to be found between connectivity patterns and performance or education as a function of age. We propose that investigation of functional connectivity in aging cannot solely rely on resting-state imaging data, especially when interpretation of behavioral data (performance) is at stake.  Our results challenge the current models of aging. We find no evidence of traditional compensation-related mechanisms in regards with preserved performance, which suggests a unique signature of semantic networks connectivity in aging.

Topic Area: Meaning: Lexical Semantics

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