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Graded Functional Organization in the Left Inferior Frontal Gyrus: Evidence From Task-Free Functional Connectivity And Task-Based Coactivation

Poster C14 in Poster Session C, Friday, October 7, 10:15 am - 12:00 pm EDT, Millennium Hall
Also presenting in Poster Slam C, Friday, October 7, 10:00 - 10:15 am EDT, Regency Ballroom

Veronica Diveica1, Michael Riedel2, Taylor Salo3, Angela Laird2, Rebecca Jackson4, Richard Binney1; 1School of Human and Behavioural Sciences, Bangor University, 2Department of Physics, Florida International University, 3Department of Psychology, Florida International University, 4MRC Cognition and Brain Sciences Unit, University of Cambridge

The left inferior frontal gyrus (IFG) has been associated with various cognitive functions, including language, executive control, and social cognition. One possibility, therefore, is that IFG subregions will reveal multiple functional specialisations. For instance, within the cognitive domain of language, functional distinctions have been proposed between the anterior IFG, thought to support semantic processes, and the posterior IFG, which has been associated with phonological processing. However, the organisation of this region and the degree to which functional differentiation occurs in a discrete or graded pattern is unclear. The aim of the present study was to explore the functional organisation of the left IFG using a data-driven approach. To this end, we first used diffusion embedding to extract connectivity gradients from 1) the resting-state fMRI timeseries of 150 participants from the Human Connectome Project, and 2) task-constrained whole-brain activation patterns across a range of tasks and cognitive domains obtained from a large database of activation coordinates. In a second step, we characterized the resulting gradients by performing seed-to-brain resting-state functional connectivity and meta-analytic coactivation modelling analyses on hard clusters extracted from the gradient maps. This allowed us to identify the connectivity patterns that drive the functional organization of the left IFG. Both datasets revealed a connectivity profile that shifted in a graded fashion along two principal organizational axes. An anterior-posterior connectivity gradient shifted from being preferentially associated with the default-mode network (anterior IFG) to ventral attention and sensorimotor networks (posterior). A second dorsal-ventral axis was characterized by higher connectivity with the frontoparietal control network on one hand (dorsal IFG), and preferential connectivity with the semantic network, on the other (ventral). These results provide novel insights into a graded organisation of the left IFG and suggest that it functions as an interface between distinct large-scale networks, with different subregions preferentially supporting the controlled access and manipulation of information in different cognitive domains. During linguistic and semantic processing, the connectivity of the anteroventral region might allow the context- and task-appropriate retrieval of conceptual knowledge.

Topic Areas: Control, Selection, and Executive Processes, Meaning: Lexical Semantics

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