The Unique Roles of the Frontal Aslant Tract in Language Processing
Year: 2018
Type: article
Abstract: Event Abstract Back to Event The Unique Roles of the Frontal Aslant Tract in Language Processing Allison J. Zhong1*, Maria Ivanova1, 2, And U. Turken1, Brian C. Curran1 and Nina F. Dronkers1, 3, 4 1 VA Northern California Health Care System, Center for Aphasia and Related Disorders, United States 2 National Research University Higher School of Economics, Center for Language and Brain, Russia 3 University of California, Davis, United States 4 University of California, Berkeley, United States In recent years, damage to a newly described tract connecting the superior and inferior frontal gyri, the frontal aslant tract (FAT), has been implicated in various disorders of the language system including stuttering disorders (Kemerdere et al., 2016; Misaghi, Zhang, Gracco, De Nil, & Beal, 2018; Neef et al., 2017), opercular syndrome (Silveri et al., 2017), and morphological derivation overflow (Sierpowska et al., 2015). Most notably, in relation to aphasia, damage to the FAT has been shown to be correlated with verbal fluency outcomes in patients with PPA (Catani et al., 2013) and chronic stroke patients (Basilakos et al., 2014; Halai, Woollams, & Lambon Ralph, 2017; Li et al., 2017). In light of the diverse implications of this tract, we aim to use deterministic tractography methods to more comprehensively investigate the specific contributions of the FAT, and its subsegments, to language processing in post-stroke aphasic patients. Language abilities in left hemisphere stroke patients with aphasia (n=33) were tested with the Western Aphasia Battery – Revised (WAB-R, Kertesz, 2007). Diffusion-weighted MR imaging was done on a 3T scanner (64 directions, 2 mm isovoxel, b = 2000 s/mm2, 10 b0 volumes). Tractography based on the spherical deconvolution model was performed using StarTrack. The FAT was manually reconstructed with ROIs in the white matter of pars opercularis and the superior frontal gyrus (SMA/pre-SMA) (Catani et al., 2012). Each FAT was further segmented into medial and lateral subsections based on its dorsal endpoints (Figure 1). For tract metrics, lesion load, normalized volume, and Hindrance Modulated Orientation Anisotropy (HMOA; index of tract integrity similar to fractional anisotropy) were used. The relationship between tract metrics and language was tested with correlational methods. In our overall analysis, we found that only lesion load in the left FAT correlated significantly with the fluency and spontaneous speech subtests of the WAB-R. We further divided the cohort to consider two groups of patients separately: those where a FAT could and could not be reconstructed in the left hemisphere. In the first group, we found that HMOA in the left FAT again correlated with the fluency and spontaneous speech scores. That of the medial subsection of the left FAT was additionally correlated with naming while the lateral subsection did not correlate with any tests. On the other hand, the group where a FAT could not be reconstructed demonstrated a wide spread of language deficits from mild to severe, raising questions as to how these patients are able to compensate and recover their language. Overall, through a more comprehensive analysis, we confirm the relationship of the FAT to fluency. We further elucidate its relationship to spontaneous speech and naming, areas of language which have not been studied with respect to the FAT before. Additionally, we offer a segmentation of the FAT that demonstrates the greater involvement of a medial subsection in these language processes. Finally, we look at individual variation in a group where the whole tract is lost, demonstrating the need for further investigation to understand how recovery may still occur. Figure 1 References Basilakos, A., Fillmore, P. 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White matter tractography of the neural network for speech-motor control in children who stutter. Neuroscience Letters, 668(December 2017), 37–42. https://doi.org/10.1016/j.neulet.2018.01.009 Neef, N. E., Anwander, A., Bütfering, C., Schmidt-Samoa, C., Friederici, A. D., Paulus, W., & Sommer, M. (2017). Structural connectivity of right frontal hyperactive areas scales with stuttering severity. Brain, (March). https://doi.org/10.1093/brain/awx316 Sierpowska, J., Gabarrós, A., Fernandez-Coello, A., Camins, A., Castañer, S., Juncadella, M., … Rodríguez-Fornells, A. (2015). Morphological derivation overflow as a result of disruption of the left frontal aslant white matter tract. Brain and Language, 142, 54–64. https://doi.org/10.1016/j.bandl.2015.01.005 Silveri, M. C., Incordino, F., Lo Monaco, R., Bizzarro, A., Masullo, C., Piludu, F., & Colosimo, C. (2017). Neural substrates of the “low-level” system for speech articulation: Evidence from primary opercular syndrome. Journal of Neuropsychology, 11(3), 450–457. https://doi.org/10.1111/jnp.12099 Keywords: frontal aslant tract, verbal fluency task, Aphasia, Stroke, Naming deficits, spontaneous speech, tractography, tract tracing, Deterministic Tractography, Frontal Lobe, naming Conference: Academy of Aphasia 56th Annual Meeting, Montreal, Canada, 21 Oct - 23 Oct, 2018. Presentation Type: poster presentation Topic: not eligible for a student prize Citation: Zhong AJ, Ivanova M, Turken AU, Curran BC and Dronkers NF (2019). The Unique Roles of the Frontal Aslant Tract in Language Processing. Conference Abstract: Academy of Aphasia 56th Annual Meeting. doi: 10.3389/conf.fnhum.2018.228.00008 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 May 2018; Published Online: 22 Jan 2019. * Correspondence: Ms. Allison J Zhong, VA Northern California Health Care System, Center for Aphasia and Related Disorders, Mather, United States, [email protected] Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Allison J Zhong Maria Ivanova And U Turken Brian C Curran Nina F Dronkers Google Allison J Zhong Maria Ivanova And U Turken Brian C Curran Nina F Dronkers Google Scholar Allison J Zhong Maria Ivanova And U Turken Brian C Curran Nina F Dronkers PubMed Allison J Zhong Maria Ivanova And U Turken Brian C Curran Nina F Dronkers Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.
Source: Frontiers in Human Neuroscience
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,801
OpenAlex ID: W2911727163