Language：Japanese   Publisher：医歯薬出版(株)  

統合失調症の連合弛緩にみられる意味関係の異常は,これまで心理実験によリ検証されてきたが,その脳内機序は不明であった.本稿ではまず,ものの意味関係を表す"意味ネットワーク"の理輪的枠組みを概観した後,脳活動に基づく意味ネットワークの構造特性を評価した筆者らの研究を紹介する.自然動画提示下fMRI(functional MRI)データに自然言語処理アルゴリズムとエンコーディングモデリングを適用して脳内意味表象を定量化し,その類似度に基づく脳内意味ネットワークの構造を評価した.その結果,統合失調症患者の脳内意味ナットワークは健常人よりもスモールワールド性が減少し,ランダム化していることが明らかになった.本研究の手法は患者の主観的体験を脳活動から直接評価できる点で,精神科医療における新規診断・治療法開発への応用が期待される.(著者抄録)

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Other Link： https://search.jamas.or.jp/default/link?pub_year=2023&ichushi_jid=J00060&link_issn=&doc_id=20230808040013&doc_link_id=issn%3D0039-2359%26volume%3D286%26issue%3D6%26spage%3D583&url=http%3A%2F%2Fwww.pieronline.jp%2Fopenurl%3Fissn%3D0039-2359%26volume%3D286%26issue%3D6%26spage%3D583&type=PierOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00005_2.gif

Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

Objectives

Schizophrenia is a mental illness that presents with thought disorders including delusions and disorganized speech. Thought disorders have been regarded as a consequence of the loosening of associations between semantic concepts since the term “schizophrenia” was first coined by Bleuler. However, a mechanistic account of this cardinal disturbance in terms of functional dysconnection has been lacking. To evaluate how aberrant semantic connections are expressed through brain activity, we characterized large-scale network structures of concept representations using functional magnetic resonance imaging (fMRI).

Study Design

We quantified various concept representations in patients’ brains from fMRI activity evoked by movie scenes using encoding modeling. We then constructed semantic brain networks by evaluating the similarity of these semantic representations and conducted graph theory-based network analyses.

Study Results

Neurotypical networks had small-world properties similar to those of natural languages, suggesting small-worldness as a universal property in semantic knowledge networks. Conversely, small-worldness was significantly reduced in networks of schizophrenia patients and was correlated with psychological measures of delusions. Patients’ semantic networks were partitioned into more distinct categories and had more random within-category structures than those of controls.

Conclusions

The differences in conceptual representations manifest altered semantic clustering and associative intrusions that underlie thought disorders. This is the first study to provide pathophysiological evidence for the loosening of associations as reflected in randomization of semantic networks in schizophrenia. Our method provides a promising approach for understanding the neural basis of altered or creative inner experiences of individuals with mental illness or exceptional abilities, respectively.

DOI： 10.1093/schbul/sbac157

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: The coronavirus disease 2019 (COVID-19) has affected all countries in the world. Hospital workers are at high risk of mental illness, such as anxiety and depression. Furthermore, they also face many social stresses, such as deterioration of human relations and income reduction. Apart from mental illness, these social stresses can reduce motivation and lead to voluntary absenteeism, which contribute to a collapse of medical systems. Thus, for maintaining medical systems, it is crucial to clarify risk factors for both mental illness and increased social stress among hospital workers. However, little attention has been paid to factors affecting social stress, and thus, we aimed to address this gap. METHODS: In this cross-sectional survey of 588 hospital workers, the levels of anxiety, depression, and social stress were assessed using the 7-item Generalized Anxiety Disorder scale (GAD-7), 9-item Patient Health Questionnaire (PHQ-9), and Tokyo Metropolitan Distress Scale for Pandemic (TMDP). Multiple regression analyses were conducted to identify the demographic variables affecting these problems. RESULTS: Older age and female sex were common risk factors for anxiety, depression, and social stress. Moreover, occupational exposure to COVID-19 and hospital staff other than doctors/fewer non-work days were risk factors for increased anxiety and depression, respectively. Furthermore, living with families/others was a risk factor for increased social stress during this pandemic. CONCLUSION: Our findings could be useful for developing policies and practices to minimize the risk of mental illness and increased social stress among hospital workers, highlighting that attention should be paid to social factors, such as an individual's household situation.

DOI： 10.1016/j.jpsychires.2021.03.007

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/pcn.13168

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Language：Japanese   Publisher：(一社)日本総合病院精神医学会  

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Language：Japanese   Publisher：(一社)日本総合病院精神医学会  

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Publisher：Cold Spring Harbor Laboratory  

<title>Abstract</title>Schizophrenia patients often manifest semantic processing deficits. It has been proposed that these deficits stem from disorganized semantic representations in the brain. However, no study has yet examined the neural correlates of semantic disorganization by directly evaluating semantic representations in the brain. We used voxelwise modeling on functional magnetic resonance imaging signals to evaluate the semantic representations associated with several thousand words in individual patient brains. We then compared the structural properties of semantic representations to those in healthy controls. The variability of semantic representations was smaller both within individual patients and across patients compared to controls. Surrogate data analysis suggests that the observed reduction in representational variability is associated with disorganization of categorical information. To our knowledge, these findings provide the first evidence for sematic disorganization in schizophrenia at the level of brain representations.

DOI： 10.1101/2020.06.03.132928

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Language：Japanese   Publisher：日本視覚学会  

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Language：English   Publishing type：Research paper (scientific journal)  

Although the relationship between schizophrenia spectrum disorder (SSD) and autism spectrum disorder (ASD) has long been debated, it has not yet been fully elucidated. The authors quantified and visualized the relationship between ASD and SSD using dual classifiers that discriminate patients from healthy controls (HCs) based on resting-state functional connectivity magnetic resonance imaging. To develop a reliable SSD classifier, sophisticated machine-learning algorithms that automatically selected SSD-specific functional connections were applied to Japanese datasets from Kyoto University Hospital (N = 170) including patients with chronic-stage SSD. The generalizability of the SSD classifier was tested by 2 independent validation cohorts, and 1 cohort including first-episode schizophrenia. The specificity of the SSD classifier was tested by 2 Japanese cohorts of ASD and major depressive disorder. The weighted linear summation of the classifier's functional connections constituted the biological dimensions representing neural classification certainty for the disorders. Our previously developed ASD classifier was used as ASD dimension. Distributions of individuals with SSD, ASD, and HCs s were examined on the SSD and ASD biological dimensions. We found that the SSD and ASD populations exhibited overlapping but asymmetrical patterns in the 2 biological dimensions. That is, the SSD population showed increased classification certainty for the ASD dimension but not vice versa. Furthermore, the 2 dimensions were correlated within the ASD population but not the SSD population. In conclusion, using the 2 biological dimensions based on resting-state functional connectivity enabled us to discover the quantified relationships between SSD and ASD.

DOI： 10.1093/schbul/sbaa021

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Language：English   Publishing type：Research paper (scientific journal)  

Recent studies examining electroconvulsive therapy (ECT) have reported that early sessions can induce rapid antidepressant and antipsychotic effects, and the early termination of ECT was reported to increase the risk of relapse. We hypothesized that different neural mechanisms associated with the therapeutic effects of ECT may be involved in the different responses observed during the early and late periods of ECT treatment. We investigated whether these antidepressant and antipsychotic effects were associated with temporally and spatially different regional gray matter volume (GMV) changes during ECT. Fourteen patients with major depressive disorder, with or without psychotic features, underwent 3-Tesla structural magnetic resonance imaging scans before (time point [Tp] 1), after the fifth or sixth ECT session (Tp2), and after ECT completion (Tp3). We investigated the regions in which GMV changed between Tp1 and Tp2, Tp2 and Tp3, and Tp1 and Tp3 using voxel-based morphometry. In addition, we investigated the association between regional GMV changes and improvement in depressive or psychotic symptoms. GMV increase in the left superior and inferior temporal gyrus during Tp1-Tp2 was associated with improvement in psychotic symptoms (P < 0.025). GMV increase in the left hippocampus was associated with improvement of depressive symptoms in Tp2-Tp3 (P < 0.05). Our findings suggest that different temporal lobe structures are associated with early antipsychotic and late antidepressant effects of ECT.

DOI： 10.1038/s41398-020-01025-8

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Language：English   Publishing type：Research paper (scientific journal)  

Team sports activities are effective for improving the negative symptoms and cognitive functions in patients with schizophrenia. However, the interpersonal coordination during the sports and visual cognition of patients with schizophrenia who have team sports habits are unknown. The main objectives of this study were to test two hypotheses: first, patients with schizophrenia perform the skill requiring ball passing and receiving worse than healthy controls; and second, the patients will be impaired in these functionings in accordance with the previous studies regarding schizophrenia in general. Twelve patients with schizophrenia and 15 healthy controls, who had habits in football, participated in this study. The participants performed three conventional cognitive tests and a 3-vs-1 ball possession task to evaluate their interpersonal coordination. The results showed that in the 3-vs-1 possession task, the displacement in the pass angle for the patients was significantly smaller than that for the control. The recall in the complex figure test, the performance in the trail making test, and that in the five-choice reaction task for the patients were worse than those for the control. Moreover, we found the significant partial correlations in the patients between the extradimensional shift error and the pass angle as well as between the time in the trail making test and the displacement in the pass angle, whereas there was no significant correlation in the control group. This study clarified the impaired interpersonal coordination during team sports and the visual cognition of patients with schizophrenia who have team sports habits.

DOI： 10.1371/journal.pone.0241863

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：Japanese   Publisher：(公社)日本精神神経学会  

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Language：English  

DOI： 10.1080/17470919.2017.1366363

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/schbul/sbx092

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Language：Japanese   Publisher：(株)ニュー・サイエンス社  

思考障害は統合失調症の主要な症状であり、中でも連合弛緩は、概念形成、カテゴリー化、意味記憶との関連から、具象化・過包括、意味ネットワークにおける伝播異常、意味記憶の貯蔵およびアクセス障害など、さまざまな仮説が提唱されてきた。近年、fMRIを用いたエンコーディングによる高次視覚野応答のモデル化が可能となり、著者らは統合失調症における脳内意味表象の可視化・定量化を行っている。こうした計算技術は、思考という内的過程へのアプローチにおいて、精神科臨床に新たな視点をもたらすことが期待される。(著者抄録)

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Language：English   Publishing type：Research paper (scientific journal)  

Schizophrenia patients have impairments at several levels of cognition including visual attention (eye movements), perception, and social cognition. However, it remains unclear how lower-level cognitive deficits influence higher-level cognition. To elucidate the hierarchical path linking deficient cognitions, we focused on biological motion perception, which is involved in both the early stage of visual perception (attention) and higher social cognition, and is impaired in schizophrenia. Seventeen schizophrenia patients and 18 healthy controls participated in the study. Using point-light walker stimuli, we examined eye movements during biological motion perception in schizophrenia. We assessed relationships among eye movements, biological motion perception and empathy. In the biological motion detection task, schizophrenia patients showed lower accuracy and fixated longer than healthy controls. As opposed to controls, patients exhibiting longer fixation durations and fewer numbers of fixations demonstrated higher accuracy. Additionally, in the patient group, the correlations between accuracy and affective empathy index and between eye movement index and affective empathy index were significant. The altered gaze patterns in patients indicate that top-down attention compensates for impaired bottom-up attention. Furthermore, aberrant eye movements might lead to deficits in biological motion perception and finally link to social cognitive impairments. The current findings merit further investigation for understanding the mechanism of social cognitive training and its development.

DOI： 10.1016/j.neures.2014.10.011

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