Identification of neural curren source domains by combining the non-invasimeasurement of the conductivity and magnetoencephalography

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H04438
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 90110:Biomedical engineering-related
• Research Institution: The University of Tokyo
• Principal Investigator: Nara Takaaki 東京大学, 大学院情報理工学系研究科, 教授 (80353423)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 逆問題 / 脳磁場 / てんかん焦点 / 磁気共鳴画像 / 導電率 / 誘電率

Outline of Final Research Achievements

This research proposed a method for the magnetoencephalography inverse problem that can separately reconstruct the localized current sources in terms of a few parameters and the background activities spread over the brain by distributed dipoles. We applied the method to an epileptic focus identification problem showing that it can reconstruct the center position and the shape of a localized current domain under the background activities, where the estimated domain coincided well with the epileptic focus identified by the electrocorticography. Also, we developed an imaging technique for estimating the electrical conductivity and permittivity inside human bodies from the magnetic field measured using magnetic resonance imaging. The proposed method forms the basis for an inversion method that considers the electrical properties of patients.

Free Research Field

逆問題

Academic Significance and Societal Importance of the Research Achievements

現在，てんかん焦点同定で用いられる等価双極子モデルは，焦点の中心位置はよく求まるが，焦点の形状，広がり具合まではわからない．本研究で開発した異種ソースモデルを用いると，背景活動源がある中でも局在電流源領域の形状まで少数パラメタで同定することができ，切除手術に対し貴重な情報を与える．また本研究で開発した導電率分布の再構成手法を導電率の周波数依存性モデルと組み合わせ，脳磁場の周波数帯域の導電率分布を推定すれば，患者・被験者ごとの電気特性を考慮した逆問題解法が実現でき，脳回・脳溝にまたがる局在電流源の推定精度が一層高まるものと期待できる．