グリア・ニューロンから見る，ヒト脳における部分てんかん発作の発振現象

The Oscillatory Phenomena in Human Epileptic Seizure: From A Glial-Neuronal Function Perspective in the Brain

脳はさまざまな帯域の脳波活動をつくり出す精巧な超LSI回路であり，これが発作的に暴走した状態のひとつとして知られるのがてんかん発作である。もっぱら神経細胞の過剰興奮に起因するとされてきたが，近年ではこれまで静的細胞とみなされていたグリア細胞が担う，てんかん原性獲得における重要な役割が注目されている。本稿では，発振現象から見る，てんかんにおけるグリア細胞と神経細胞（ニューロン）の両者の相補的・共起的な働きについて概説を行う。

Abstract

The brain is a kind of very large-scale integration circuit or its beyond that produces extremely various ranges of electroencephalogram. Epilepsy is a state caused by explosively hyperexcitable brain activities. Recently, it has been suggested that not only the hyperexcitability of neurons but also glial cells, which were previously thought to be silent or plain, play a crucial role in the acquisition of epileptogenicity. In this review article, we will comprehensively describe the utility of the analysis of brain activities from extremely low to high frequency oscillations. Our multi-institute study confirmed that ictal direct current shifts (ictal DC) precedes ictal high-frequency oscillations (ictal HFOs), being more prominent in neocortical epilepsy than in temporal lobe epilepsy. Moreover, we revealed that the complete resection of the core regions of ictal DC shifts significantly correlated with favorable outcomes after epileptic surgery. Taking our findings and previous knowledge into account, we will address the importance of not only neuronal but also glial functions towards the better understanding of pathogenesis of the so-called “chronic” state of epilepsy.