Evaluation of cortical functions in CI children by fNIRS

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K11326
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Otorhinolaryngology
• Research Institution: Kyoto University
• Principal Investigator: Yamazaki Hiroshi 京都大学, 医学研究科, 客員研究員 (80536243)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: fNIRS / 多チャンネル脳波計 / 聴覚野

Outline of Final Research Achievements

In normal hearing participants, fNIRS revealed left side-dominant activation in the auditory cortex which was induced by speech sounds. In the CI users, however, fNIRS signals evoked by CI stimulation varied widely between cases probably because between-subject difference in thickness of subcutaneous tissue and cranial bone might affect fNIRS signals. Thus,instead of fNIRS, we used multi-channel EEG to estimate dipole moments in auditory corticies. Left-dominant cortical activation was induced by speech sounds, but not by tone sounds. Furthermore, EEG analysis detected synchronized cortical activities between auditory cortex and visual corteices were detected during audito-visual integration tasks, which was more obvious in participants who showed higher audito-visual integration. These analysis can be adopted to CI users to evaluate development of cortical activities and left-right asymmetricitiy which are induced by CI-mediated auditory signals.

Free Research Field

人工内耳

Academic Significance and Societal Importance of the Research Achievements

先天性難聴者では聴覚に関連した中枢神経回路の発達が傷害されると考えられている。人工内耳を介した音声入力は、部分的ではあるが聴覚関連中枢神経回路の発達を促すと考えられているがその詳細は不明である。人工内耳装用者はMRIを用いた脳機能評価が困難であるため、我々は人工内耳装用者でも施行可能なfNIRSと脳波計を用いて聴覚関連脳機能画像評価を行った。その結果、fNIRS検査では頭皮から脳表までの組織性状が検査結果に大きく影響するため注意が必要であること示唆された。一方、脳波検査では聴覚野賦活化だけでなく聴覚野と視覚野の同期的活動も検出することができ、今後人工内耳装用者に応用可能と考えられた。