Grant-in-Aid for Scientific Research (A)
|Research Institution||TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY|
ONO Taketoshi Toyama Medical and Parmaceutical University, Department of Physiology, Professor, 医学部, 教授 (50019577)
OKAMOTO Yoshio Chiba Industrial Univ., Department of Electronics, Professor, 電気工学科, 助教授 (20152358)
HOMMA Ikuo Showa University Medical School, Department of Physiology, Professor, 医学部, 教授 (20057079)
NAKAJIMA Yoshio Chiba University, Medical School, Department of Physiology, Professor, 医学部, 教授 (60092079)
HOMMA Saburo Meiji University of Oriental Medicine Graduate School of Oriental Mdicine, Profe, 大学院, 研究科長 (70009075)
NISHIJO Hisao Toyama Medical and Parmaceutical University, Department of Physiology, Associate, 医学部, 助教授 (00189284)
|Project Fiscal Year
1995 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥6,100,000 (Direct Cost : ¥6,100,000)
Fiscal Year 1997 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Fiscal Year 1996 : ¥4,700,000 (Direct Cost : ¥4,700,000)
|Keywords||Dipole tracing / SSLB / Realistic head model / Boundary element method / EEG / VEP / SEP / Epilepsy / 双極子追跡法 / 境界要素法 / 頭部実形状モデル / 双極子 / 超音波位置検出センサー / 視覚誘発電位 / 体性感覚誘発電位 / てんかん焦点 / 体性間覚誘発電位 / 非侵襲法 / 脳波 / 誘発電位 / てんかん波 / 実形状4層モデル / サル / ヒト|
To localize current source generators (dipoles) of EEGs and evoked potentials, a dipole tracing (DT) method with a realistic 4-layr (scalp-skull-liquor-brain : SSLB) head model (SSLB/DT method) was developed.
1. Manufacturing of a liquid crystal shutter
The duration of the visual stimulus for visually evoked potentials (VEPs) was controlled by a liquid crystal shtter, which was positioned before the projector and driven by an operation amplifier. The shutter changed from opaque to transparent within a span of 0.5 msec when a driving voltage pulse from the operation amplifier was on.
2. Manufacturing of 3-D measurement device for a head model
A3-D measurement system using a sonic generator and receiver was developed. A realistic head model was reconstructed on a workstation using this system, and 3-D coordinations of electrodes on a head were also measured by this system.
3. Development of the SSLB/DT method
The algorithm for the SSLB/DT method incorporating a realistic 4-layr head model was
developed. The SSLB/DT method can, by a boundary element method, equate the surface potential distributions on a scalp to one or two corresponding equivalent dipoles. The software for the SSLB/DT method was adjusted optimally to run on a parallel computer.
4. Neurophysiological studies
1) Dipoles of the human VEPs to visual stimuli were investigated with the SSLB/DT method. The results indicated topographic localization of the dipoles around the calcarine fissure based on the loci of the visual fields. This was comparable to the retinotopy of the human occipital lobe based on clinicopathological studies. 2) To localize ictal onset zone, the SSLB/DT was applied to ictal EEGs. Comparison of the results by the SSLB/DT method and the electrocorticograms confirmed that the SSLB/DT method could accurately localize dipoles even when a subject has an enlarged subdural liquor space due to neurosurgical operation or brain atrophy. 3) Somatosensory evoked potentials (SEPs) elicited by right posterior tibial nerve stimulation were recorded from epidural electrodes in 3 monkeys, and analyzed by the DT method. Dipoles of these SEPs were located in the left side of the mesial wall of the anterior parietal cortex, and oriented obliquely toward the right hemisphere. Less