title: Effects of sex and proficiency in second language processing as revealed by a large-scale fNIRS study of school-aged children.
abstract: Previous neuroimaging studies in adults have revealed that first and second languages (L1/L2) share similar neural substrates, and that proficiency is a major determinant of the neural organization of L2 in the lexical-semantic and syntactic domains. However, little is known about neural substrates of children in the phonological domain, or about sex differences. Here, we conducted a large-scale study (n = 484) of school-aged children using functional near-infrared spectroscopy and a word repetition task, which requires a great extent of phonological processing. We investigated cortical activation during word processing, emphasizing sex differences, to clarify similarities and differences between L1 and L2, and proficiency-related differences during early L2 learning. L1 and L2 shared similar neural substrates with decreased activation in L2 compared to L1 in the posterior superior/middle temporal and angular/supramarginal gyri for both sexes. Significant sex differences were found in cortical activation within language areas during high-frequency word but not during low-frequency word processing. During high-frequency word processing, widely distributed areas including the angular/supramarginal gyri were activated in boys, while more restricted areas, excluding the angular/supramarginal gyri were activated in girls. Significant sex differences were also found in L2 proficiency-related activation: activation significantly increased with proficiency in boys, whereas no proficiency-related differences were found in girls. Importantly, cortical sex differences emerged with proficiency. Based on previous research, the present results indicate that sex differences are acquired or enlarged during language development through different cognitive strategies between sexes, possibly reflecting their different memory functions.
authors.affiliation: Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo, 192-0397, Japan.|Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Niban-Cho, Chiyoda-Ku, Tokyo, 100-0004, Japan.|Research Center for Language, Brain and Genetics, Tokyo Metropolitan University.
authors.forename: Lisa
authors.initials: L
authors.lastname: Sugiura
authors.affiliation: Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo, 192-0397, Japan.|Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Niban-Cho, Chiyoda-Ku, Tokyo, 100-0004, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Ojima
authors.affiliation: Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Niban-Cho, Chiyoda-Ku, Tokyo, 100-0004, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Matsuba-Kurita
authors.affiliation: Applied Cognitive Neuroscience Lab, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-Ku, Tokyo, 112-8551, Japan.
authors.forename: Ippeita
authors.initials: I
authors.lastname: Dan
authors.affiliation: Applied Cognitive Neuroscience Lab, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-Ku, Tokyo, 112-8551, Japan.|Information Science and Technology Department, National Institute of Technology, Yuge College, 1000 Shimoyuge, Yuge, Kamijima-cho, Ochi-gun, Ehime, 794-2593, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tsuzuki
authors.affiliation: Center for Exploratory Research, Research & Development Group, Hitachi, Ltd., Hatoyama, Saitama, 350-0395, Japan.
authors.forename: Takusige
authors.initials: T
authors.lastname: Katura
authors.affiliation: Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo, 192-0397, Japan.|Research Institute of Science and Technology for Society (RISTEX), Japan Science and Technology Agency (JST), Niban-Cho, Chiyoda-Ku, Tokyo, 100-0004, Japan.|Research Center for Language, Brain and Genetics, Tokyo Metropolitan University.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hagiwara
mesh_terms: D000375:Aging / Q000502:physiology; D000465:Algorithms; D002540:Cerebral Cortex / Q000254:growth & development / Q000502:physiology; D002648:Child; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007807:Language Tests; D008297:Male; D008568:Memory / Q000502:physiology; D019303:Multilingualism; D059906:Neuroimaging; D011597:Psychomotor Performance / Q000502:physiology; D012727:Sex Characteristics; D019265:Spectroscopy, Near-Infrared
keywords: children; first/native language (L1); functional near-infrared spectroscopy; learning; memory; phonological familiarity; phonology; proficiency; second language (L2); sex differences