A neurocognitive investigation of mechanism underlying auditory verbal hallucination

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K22286
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0110:Psychology and related fields
• Research Institution: Kyushu University
• Principal Investigator: Tamura Shunsuke 九州大学, 医学研究院, 特任助教 (20883333)
• Project Period (FY): 2020-09-11 – 2022-03-31
• Keywords: 神経オシレーション / 統合失調症 / 音声 / 脳波 / 脳磁図

Outline of Final Research Achievements

In this study, we examined abnormalities of neural oscillations in responses to speech sounds in schizophrenia patients as a preliminary step to elucidate the mechanism of auditory verbal hallucination. We analyzed the degree of stimulus-synchronization of θ and γ oscillations, which are phase-locked to the slow temporal fluctuation (amplitude envelope) and fast temporal fluctuation (temporal fine structure) in speech signals, respectively. The results showed that the degree of stimulus phase-locking was decreased in schizophrenia patients compared to normal controls in both θ and γ oscillations. The significant positive correlation between θ and γ oscillations, which was confirmed in normal controls, was also not observed in schizophrenia patients. It was also found that the degree of abnormality of γ oscillation can predict the severity of symptoms related to thoughts and delusions.

Free Research Field

認知神経科学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果として, 統合失調症における言語音声聴取時の神経オシレーション異常を明らかにすることが出来た。言語性幻聴のメカニズムを検討する上で, 「統合失調症者に見られる自発発火や内言の異常が言語性幻聴を引き起こすのであれば, それらの異常に関連する脳活動は実際に音声を聴いている時の脳活動と類似した特徴を持つ」という仮説を立てており, 今回の成果はこの仮説の検討の足掛かりになると考えている。さらに, γオシレーションの異常が思考・妄想に関わる症状と強く相関するという結果は, 言語音声を用いた神経オシレーションの計測が統合失調症の診断や症状の予測にも有用である可能性が示唆される。