Discharge threshold is enhanced for several seconds after a single interictal spike in a model of focal epileptogenesis
Discharge threshold is enhanced for several seconds after a single interictal spike in a model of focal epileptogenesis
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DOI：
10.1046/j.0953-816x.2001.01637.x
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发表时间：
2001-07-01
影响因子：
3.4
通讯作者：
Biella, G
中科院分区：
文献类型：
--
作者：
de Curtis, M;Librizzi, L;Biella, G
在局灶性癫痫的发作之间通常观察到发作间期棘波（IS）。在向发作性放电的过渡中，IS是否是因果关系或代表保护性因素是一个悬而未决的问题。以前的研究表明，抑制或disfacilitation发生在两个IS之间的时间流逝诱导的局部应用荷包牡丹碱或青霉素在梨状皮质的离体豚鼠脑制备。我们进一步研究了这个问题，通过研究传入刺激的反应在interspike期间（6.3 +/- 2.5秒;平均值+/- SD）。正确设置的外侧嗅束刺激强度仅在先前自发峰电位后4-10 s（5.6 +/- 2.0 s;平均值+/- SD）（而不是之前）重置IS。这一发现表明，存在一个时期的增强阈值刺激诱发的激活，在没有刺激的情况下，与interspike间隔相一致。电流源密度分析的深度层状配置文件表明，刺激诱发和自发ISs产生的激活相同的皮层电路。我们的研究表明，发作间隙尖峰可以发挥保护作用，或者至少可以有效抑制局灶性发作放电的发生。
Interictal spikes (ISs) are typically observed between seizures in focal epilepsies. Whether ISs are causally involved or represent protective elements in the transition toward an ictal discharge is an open question. Previous studies suggested that inhibition or disfacilitation occurs during the period elapsing between two ISs induced by local application of either bicuculline or penicillin in the piriform cortex of the in vitro isolated guinea pig brain preparation. We further investigated this issue by studying responses to afferent stimulation during the interspike period (6.3 +/- 2.5 s; mean +/- SD). Properly set stimulation intensity of the lateral olfactory tract resets ISs exclusively (and not before) 4-10 s (5.6 +/- 2.0 s; mean +/- SD) after a preceding spontaneous spike. This finding demonstrates the existence of a period of enhanced threshold to stimulus-evoked activation that coincides with the interspike interval in the absence of stimulation. Current source density analysis of depth laminar profiles demonstrated that both stimulus-evoked and spontaneous ISs were generated by the activation of an identical cortical circuit. Our study suggests that interictal spiking could play a protective role or at least provide an effective restraint against the onset of a focal ictal discharge.