Natsubori Tatsunobu, Hashimoto Ryu-Ichiro, Yahata Noriaki, Inoue Hideyuki, Takano Yosuke, Iwashiro Norichika, Koike Shinsuke, Gonoi Wataru, Sasaki Hiroki, Takao Hidemasa, Abe Osamu, Kasai Kiyoto, Yamasue Hidenori
Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
Department of Language Sciences, Graduate School of Humanities, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0364, Japan.
Schizophr Res. 2014 Aug;157(1-3):218-24. doi: 10.1016/j.schres.2014.05.027. Epub 2014 Jun 2.
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.
精神分裂症患者以及精神分裂症高危个体在语言处理的语义和语音方面存在障碍。为了揭示这些障碍的神经关联，先前一项使用组块设计的视觉词汇判定任务的功能磁共振成像（fMRI）研究报告称，与正常对照受试者相比，精神分裂症患者和精神病遗传高危个体的额下回左侧化程度较低。然而，据我们所知，以前没有研究使用事件相关设计的视觉词汇判定fMRI任务，在精神病超高危（UHR）受试者和精神分裂症患者中，调查单词与非单词处理之间的对比，从而区分语义和语音处理。在本研究中，20名精神分裂症患者、11名UHR个体和20名人口统计学匹配的对照者接受了词汇判定fMRI任务。与对照组相比，精神分裂症组和UHR组在额下区域对非单词的反应活动均显著低于对单词的反应活动。此外，与对照组相比，UHR受试者在非单词与单词活动对比中左侧化程度降低，而在精神分裂症患者中并不明显。本研究结果表明，与单词处理相比，非单词处理过程中语言处理语音方面困难的神经关联，这至少部分共同构成了精神分裂症和UHR病理生理学的基础。与先前对遗传高危受试者的研究一起，当前结果还表明，语言相关额叶皮层功能侧化降低可能是精神分裂症的一个易感性标志物。此外，当前结果可能表明，精神病的遗传基础被认为与人类语言能力特征的进化有关。
