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Anatomical Connectivity of the Cingulum Bundle and its Role in Bilingual Cognitive Control
Poster Session C, Thursday, October 1, 10:45 am - 12:45 pm, Wangari Maathai
Hannah Kogan1,2,3,6, Elise Barbeau1,2,3, Jen-Kai Chen1,2,3, Michael Petrides1,2,3,5, Shanna Kousaie4, Shari Baum3,6, Denise Klein1,2,3; 1Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada., 2Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada., 3Centre for Research on Brain, Language, and Music (CRBLM), Montreal, Quebec, Canada., 4School of Psychology, University of Ottawa, Ottawa, Ontario, Canada., 5Department of Psychology, McGill University, Montreal, Quebec, Canada., 6School of Communication Sciences and Disorders, McGill University, Montreal, Quebec, Canada.
The cingulum bundle is a major frontal-limbic white matter tract implicated in cognitive control. Cognitive control encompasses processes such as inhibition, conflict monitoring, and monitoring within working memory that support goal-directed behaviour across changing task demands. Developmental experiences that place sustained demands on cognitive control systems may contribute to the specialization of these networks. Bilingual language use has been proposed as one such influence, particularly in simultaneous bilinguals who engage in dual-language management from birth. Using diffusion-weighted imaging (DWI), the present study examined whether volumetric and microstructural properties of cingulum sub-connections are differentially associated with performance across cognitive control tasks varying in executive demands. Characterizing how the cingulum bundle dissociates across cognitive control processes may provide a framework for understanding how developmental experiences, such as bilingual language exposure, shape control-related neural systems. DWI and cognitive control task performance data were analyzed from 50 French–English bilingual participants. After excluding two participants with extreme outlier values, the final sample consisted of 48 participants. The behavioural tasks administered were the Simon Task, Digit Span (forward, backward, sequential), Letter Number Sequencing, Letter Fluency, Category Fluency, and Matrix Reasoning. Manual tract dissection of the cingulum bundle was performed using a seed-based approach with specific regions of interest. The cingulum was dissected as a whole tract connecting frontal, medial parietal, and medial temporal regions, and further divided into its sub-connections, including the frontal–medial parietal and frontal–posterior hippocampal components. Volume and fractional anisotropy (FA) for each one of these tract components and the entire cingulum tract were extracted based on this dissection. Data were analyzed using bivariate correlation analysis. There were no associations found between cingulum volume or FA and matrix reasoning, letter fluency or simple digit span tasks (forward and backward), suggesting limited involvement of the cingulum in general intelligence, letter fluency, and basic working memory processes. In contrast, performance on more complex sequencing tasks was significantly correlated with cingulum tract volume: better sequential digit span performance was linked to lower frontal–medial parietal tract component volume, while better letter number sequencing performance was associated with greater frontal–posterior hippocampal tract component volume. Findings from the Simon Task further supported functional specialization within the cingulum, with distinct sub-connections selectively contributing to interference suppression and response inhibition. Additionally, higher category fluency scores were bilaterally associated with greater frontal–posterior hippocampal tract component volume, suggesting a role for this sub-connection in semantic memory and retrieval. The preliminary findings suggest that the cingulum bundle plays a dissociable, task-dependent role in cognitive control that varies across its sub-connections. The results indicate that the cingulum bundle is not a unitary structure, but rather a network of distinct sub-connections that support different aspects of cognitive control. Subsequent analyses will examine the potential mediating effect of second language acquisition on these associations, thus extending this framework to theories of bilingualism.
Topic Areas: Control, Selection, and Executive Processes, Language Development/Acquisition