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Poster E56, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Multimodal MRI converging evidence on the role of ventro-occipito-temporal cortex in reading: Integrating opposing views

Garikoitz Lerma-Usabiaga1, Carreiras Manuel1,2, Paz-Alonso Pedro M.1;1BCBL. Basque Center on Cognition, Brain and Language, Donostia-San Sebastián, Spain, 2IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.

The ventral occipito-temporal (vOT) association cortex significantly contributes to recognize different types of visual patterns. It is widely accepted that a subset of this circuitry becomes trained to perform the task of rapidly identifying word-forms. However, there are still important open questions unanswered: how is the functional contribution of the different cortical regions within the vOT to the visual word recognition? Does function relate to the structural connectivity of vOT regions with other language areas? There are previous reports of functional dissociations along the vOT. Furthermore, while some authors report structural connections between the vOT and the posterior parietal cortex (pPC) via the vertical occipital fasciculus, others highlight more anterior vOT-pPC structural connections through the posterior arcuate fasciculus. Characterizing the vOT connectivity pattern can be critical to shed further light on the computational role of the VWFA. Here we present the results of a multimodal (functional, diffusion-weighted and quantitative) study including 97 MRI sessions with young adults aimed at investigating the functional and structural connectivity patterns of the vOT reading regions. To examine how functional contrasts influence the location of the VWFA, we used those that have been reported more often in the literature. Furthermore, due to the large intraindividual variability, our analyses were performed at the individual-subject level, and half of the subjects were scanned twice to check for test-retest reliability. Finally, we examined the contribution of the vOT regions to word, pseudo-word and consonant string reading. Our results revealed a functional segregation along the anterior-posterior vOT, across different functionals contrast and that was concurrently associated with differences in vOT-pPC structural connectivity. Reading behavior was predicted by functional activation in these vOT regions and by the structural properties of the white matter fiber tracts linking vOT with other regions within the reading network. We propose a new subdivision of the vOT reading regions. Our findings constitute a step forward in the pre-lexical/lexical discussion regarding the role of the vOT in reading, suggesting the existence of an anterior and a posterior VWFAs with clearly differentiated functional roles and with white matter connectivity with different pPC regions.

Topic Area: Perception: Orthographic and Other Visual Processes

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