title: White matter pathway supporting phonological encoding in speech production: a multi-modal imaging study of brain damage patients.
abstract: In speech production, an important step before motor programming is the retrieval and encoding of the phonological elements of target words. It has been proposed that phonological encoding is supported by multiple regions in the left frontal, temporal and parietal regions and their underlying white matter, especially the left arcuate fasciculus (AF) or superior longitudinal fasciculus (SLF). It is unclear, however, whether the effects of AF/SLF are indeed related to phonological encoding for output and whether there are other white matter tracts that also contribute to this process. We comprehensively investigated the anatomical connectivity supporting phonological encoding in production by studying the relationship between the integrity of all major white matter tracts across the entire brain and phonological encoding deficits in a group of 69 patients with brain damage. The integrity of each white matter tract was measured both by the percentage of damaged voxels (structural imaging) and the mean fractional anisotropy value (diffusion tensor imaging). The phonological encoding deficits were assessed by various measures in two oral production tasks that involve phonological encoding: the percentage of nonword (phonological) errors in oral picture naming and the accuracy of word reading aloud with word comprehension ability regressed out. We found that the integrity of the left SLF in both the structural and diffusion tensor imaging measures consistently predicted the severity of phonological encoding impairment in the two phonological production tasks. Such effects of the left SLF on phonological production remained significant when a range of potential confounding factors were considered through partial correlation, including total lesion volume, demographic factors, lesions on phonological-relevant grey matter regions, or effects originating from the phonological perception or semantic processes. Our results therefore conclusively demonstrate the central role of the left SLF in phonological encoding in speech production.
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, 100875, China. zzhhan@bnu.edu.cn.|Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing, 100875, China. zzhhan@bnu.edu.cn.
authors.forename: Zaizhu
authors.initials: Z
authors.lastname: Han
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, 100875, China.|Department of Psychology, Henan University, Kaifeng, 475000, China.
authors.forename: Yujun
authors.initials: Y
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, 100875, China.|Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing, 100875, China.
authors.forename: Gaolang
authors.initials: G
authors.lastname: Gong
authors.affiliation: Center for the Study of Applied Psychology, Key Laboratory of Mental Health and Cognitive Science of Guangdong Province, School of Psychology, South China Normal University, Guangzhou, 510631, China.
authors.forename: Ruiwang
authors.initials: R
authors.lastname: Huang
authors.affiliation: Department of Neuro-rehabilitation, Rehabilitation College of Capital Medical University and China Rehabilitation Research Center, Beijing, 100068, China. songluping882002@yahoo.com.cn.
authors.forename: Luping
authors.initials: L
authors.lastname: Song
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, 100875, China.|Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing, 100875, China.
authors.forename: Yanchao
authors.initials: Y
authors.lastname: Bi
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D001037:Aphasia / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D001930:Brain Injuries / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D001931:Brain Mapping / Q000379:methods; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D009483:Neuropsychological Tests; D010700:Phonetics; D011932:Reading; D012660:Semantics; D013060:Speech; D020521:Stroke / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D014825:Vocabulary; D066127:White Matter / Q000473:pathology* / Q000503:physiopathology*; D055815:Young Adult
keywords: Connectome; Diffusion tensor imaging; Left superior longitudinal fasciculus; Patients; Phonological encoding