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Poster C55, Thursday, November 9, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Age-related brain activation changes during rule repetition in word-matching

Ikram Methqal1, Basile Pinsard1, Maximiliano A. Wilson2, Oury Monchi3, Jean-Sebastien Provost3, Mahnoush Amiri1, Yves Joanette1;1Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, Québec, Canada, 2Centre de Recherche de l’Institut Universitaire en Santé Mentale de Québec, QC, Canada, 3Hotchkiss Brain Institute, University of Calgary, Calgary, Canada

Objective: One of the most used paradigms to explore the ability to apply category-based rules consists in a rule-based category-learning task which requires to make a repeated feedback-driven selection using a given category-based criterion over time. In the area of language, a complex and common rule-based task used has been adapted from the Wisconsin Sorting Card Test. Given the semantic advantage associated with healthy aging, it was expected that the use of such a task in older participants, while acquiring neurofunctional data, would provide some insight into the life-course’s adaptive neurofunctional reorganization. The purpose of this study was thus to explore the age-related brain activation changes during a word-matching semantic-category based task. Method: Two groups of healthy adults (20 younger adults and 20 older adults) performed a word-matching task while undergoing a fMRI scan in which they were required to pair a target word with another word amongst three reference cards based on three semantic rules and corresponding to different level of semantic control demands: functional relatedness, moderately typical-relatedness which were considered as low control demands, and atypical-relatedness that was considered as high control demand. The sorting period required a continuous execution of the same sorting rule for a longer period and an inferred trial-by-trial feedback was given. Results: Behavioral performance revealed increases in response times and decreases of correct responses according to the level of semantic control demands (functional vs typical vs atypical) for both age-groups (younger and older) reflecting graded differences in the repetition of the application of a given semantic rule. Neuroimaging findings of significant brain activation showed two principal results: 1) Task-related activation changes in inferior temporal regions bilaterally for the repetition of the application of atypical rule relative to functional and typical. 2) Direct comparisons (older > younger) revealed age-related activation in the left anterior lateral prefrontal cortex for functional and at a greater extent and bilaterally for typical and atypical rule. However, for general semantic processing comparison, only task-related activation changes were found in parieto-temporal regions for functional rule repetition relative to typical and at a greater extent in right frontal and temporal regions for atypical rule repetition relative to typical. Conclusion: These results suggest that successful cognitive aging relies on the adaptive changes of prefrontal resources involved in the continuous execution of semantic rule according to complexity of the semantic relationship. However, activation changes in semantic networks engaged in general semantic processing appears to be related to a word-matching task than to age per se.

Topic Area: Meaning: Lexical Semantics

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