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Brain oscillations in its physiology and pathophysiology

開催日 2014/9/11
時間 9:00 - 11:00
会場 Room C(502)
Chairperson(s) 池田 昭夫 / Akio Ikeda (京都大学大学院医学研究科 てんかん・運動異常生理学講座 / Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Japan)
美馬 達哉 / Tatsuya Mima (京都大学大学院医学研究科附属脳機能総合研究センター / Human Brain Research Center, Kyoto University Graduate School of Medicine, Japan)

Hippocampal network dynamics in optogenetically induced seizure model

  • S1-C-1-2
  • 岩崎 真樹 / Masaki Iwasaki:1 大沢 伸一郎 / Shin-ichiro Osawa:1 保坂 亮介 / Ryosuke Hosaka:2 松坂 義哉 / Yoshiya Matsuzaka:3 富田 浩史 / Hiroshi Tomita:4 石塚 徹 / Toru Ishizuka:5 菅野 江里子 / Eriko Sugano:4 奥村 栄一 / Eiichi Okumura:6 八尾 寛 / Hiromu Yawo:5 中里 信和 / Nobukazu Nakasato:6 冨永 悌二 / Teiji Tominaga:1 虫明 元 / Hajime Mushiake:3 
  • 1:東北大学大学院医学系研究科神経外科学分野 / Department of Neurosurgery, Tohoku University Graduate School of Medicine, Japan 2:福岡大学応用数理学科 / Department of Applied Mathematics, Fukuoka University, Fukuoka, Japan 3:東北大学大学院医学系研究科生体システム生理学分野 / Department of Physiology, Tohoku University Graduate School of Medicine, Sendai, Japan 4:岩手大学工学部応用化学・生命工学科生命工学分野 / Department of Chemistry and Bioengineering, Faculty of Engineering, Graduate School of Science and Engineering, Iwate University, Morioka, Japan 5:東北大学大学院生命科学研究科脳機能解析分野 / Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences,  6:東北大学大学院医学系研究科てんかん学分野 / Department of Epileptology, Tohoku University Graduate School of Medicine, Japan 

Epileptic seizure is a paroxysmal and self-limited phenomenon characterized by abnormal hypersynchrony of a large population of neurons. However, our current understanding of seizure dynamics is still limited. Here we propose a novel in vivo model of seizure-like afterdischarges using optogenetics, and report on investigation of directional network dynamics during seizure along the septo-temporal (ST) axis of hippocampus. Repetitive pulse photostimulation was applied to the rodent hippocampus, in which channelrhodopsin-2 (ChR2) was expressed, under simultaneous recording of local field potentials (LFPs). LFPs were recorded during seizure-like afterdischarges with a multi-contact array electrode inserted along the ST axis of hippocampus. Granger causality analysis of the LFPs showed a bidirectional but asymmetric increase in signal flow along the ST direction. State space presentation of the causality and coherence revealed three discrete states of the seizure-like afterdischarge phenomenon: 1) resting state; 2) afterdischarge initiation with moderate coherence and dominant septal-to-temporal causality; and 3) afterdischarge termination with increased coherence and dominant temporal-to-septal causality. A novel in vivo model of seizure-like afterdischarge using optogenetics is advantageous in its reproducibility and artifact-free electrophysiological observations. Our results suggest the potential role of hippocampal septo-temporal interactions in seizure dynamics. Bidirectional networks work hierarchically along the ST hippocampus in the genesis and termination of epileptic seizures.

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