title: An fMRI study of visual lexical decision in patients with schizophrenia and clinical high-risk individuals.
abstract: Disturbances in semantic and phonological aspects of language processing are indicated in patients with schizophrenia, and in high-risk individuals for schizophrenia. To uncover neural correlates of the disturbances, a previous functional magnetic resonance imaging (fMRI) study using a visual lexical decision task in block design reported less leftward lateralization in the inferior frontal cortices, in patients with schizophrenia and individuals with high genetic risk for psychosis compared with normal control subjects. However, to our knowledge, no previous study has investigated contrasts between word and non-word processing that allow dissociation between semantic and phonological processing using event-related design visual lexical decision fMRI tasks in subjects with ultra-high-risk for psychosis (UHR) and patients with schizophrenia. In the current study, 20 patients with schizophrenia, 11 UHR, and 20 demographically matched controls underwent lexical decision fMRI tasks. Compared with controls, both schizophrenia and UHR groups showed significantly decreased activity in response to non-words compared with words in the inferior frontal regions. Additionally, decreased leftward lateralization in the non-word compared with word activity contrast was found in subjects with UHR compared with controls, which was not evident in patients with schizophrenia. The present findings suggest neural correlates of difficulty in phonological aspects of language processing during non-word processing in contrast to word, which at least partially commonly underlies the pathophysiology of schizophrenia and UHR. Together with a previous study in genetic high-risk subjects, the current results also suggest that reduced functional lateralization in the language-related frontal cortex may be a vulnerability marker for schizophrenia. Furthermore, the current result may suggest that the genetic basis of psychosis is presumed to be related to the evolution of the language capacity characteristic of humans.
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Tatsunobu
authors.initials: T
authors.lastname: Natsubori
authors.affiliation: Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0364, Japan.
authors.forename: Ryu-Ichiro
authors.initials: R
authors.lastname: Hashimoto
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Yahata
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Inoue
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Takano
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Norichika
authors.initials: N
authors.lastname: Iwashiro
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; Office for Mental Health Support, Division for Counseling and Support, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Koike
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Gonoi
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sasaki
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Takao
authors.affiliation: Department of Radiology, Nihon University School of Medicine, 30-1 Oyaguchi kami-cho, Itabashi-ku, Tokyo 173-8610, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Abe
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. Electronic address: yamasue-tky@umin.ac.jp.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Yamasue
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000503:physiopathology*; D003657:Decision Making / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D010700:Phonetics; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000503:physiopathology*; D012306:Risk; D012559:Schizophrenia / Q000503:physiopathology*; D012660:Semantics; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: At-risk mental state (ARMS); Biomarkers; Human; Laterality index; Magnetic resonance imaging (MRI); Psychosis