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Ly, Huan Nhat Nguyen

University of British Columbia

Functional magnetic resonance imaging (fMRI) is a powerful neuroimaging technique for studying the spatial and temporal aspects of blood-oxygen level dependent (BOLD) signal changes during performance of specifically designed tasks. To date, task-based fMRI studies have reliably identified twelve cognitive modes, which are anatomical configurations with associated functions that underlie the cognitive, sensory, and motor processes during task performance. To detect these modes, our research group has been employing a traditional method called G-matrix Constrained Principal Component Analysis for fMRI (fMRI–CPCA), which constrains the variance in BOLD signal to variance related to task timing. However, problems can arise if different modes get merged, or when a mode is poorly formed due to the substantially small variance it accounts for. By relying on the now well-established anatomical details of the twelve cognitive modes, we have developed a novel detection method called H-matrix fMRI–CPCA, which constrains the variance in BOLD signal spatially to the prototypical templates of twelve modes. To assess this new method in comparison with G-matrix fMRI–CPCA, we used both methods to analyze fMRI data for healthy adults’ performance of five selected tasks: Antonyms, Letter Comparison, Pattern Comparison, Digit Symbol, and Sensorimotor. G-matrix method produced components in which the modes were merged when they typically get separated into different components. H-matrix method redistributed these modes over more components but may have also produced Type I errors. For Antonyms, Letter Comparison, Pattern Comparison, and Digit Symbol, some merging of modes remained, and interpretation was not improved. Sensorimotor task showed better temporal and spatial separation of modes, and interpretation improved in H-matrix analysis, which was attributable to task design. Antonyms, Letter Comparison, Pattern Comparison, and Digit Symbol were designed similarly and hence shared common weaknesses, specifically the short inter-stimulus interval (0.5s or 0.25s), whereas Sensorimotor used longer intervals (2-26s jittered). Since the selected sample had a wide age range (about 20-80), age was investigated in a secondary analysis. Results from G-matrix analysis suggested that Language, Response, and Default Modes A and B showed age differences, potentially reflecting changes in vocabulary skills and cognitive processing speed associated with healthy ageing.

Text

2025-04-24

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90753

Neuroscience

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/