Single unit action potentials in humans and the effect of seizure activity
Single unit action potentials in humans and the effect of seizure activity
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DOI：
10.1093/brain/awv208
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发表时间：
2015-10-01
期刊：
影响因子：
14.5
通讯作者：
Trevelyan, Andrew J.
中科院分区：
文献类型：
--
作者：
Merricks, Edward M.;Smith, Elliot H.;Trevelyan, Andrew J.
尖峰分选算法已被用于识别孤立的神经元（“单个单位”）的放电模式，从植入的电极记录在接受评估癫痫手术的患者，但我们不知道他们的潜力，提供有用的临床信息。因此，重要的是要描述这些记录的稳定性及其背景。一个关键的考虑因素是单位位于相对于病理学的重点。最近的分析神经元尖峰活动，记录在扩展的空间区域使用微电极阵列，已经证明了考虑癫痫发作活动的重要性，在两个不同的空间领域：发作的核心和半影的领土。然而，这两个区域的病理信息可能非常不同。因此，我们调查了在这两个领域，包括在癫痫发作时期，是否可以在长时间内可靠地跟踪单位。我们从4名接受视频遥测监测的患者的几百个神经元中分离出单位记录，用于局灶性新皮层癫痫的手术评估。单位稳定性可以持续超过40小时，并在多次癫痫发作。一个关键的发现是，在半影区，即使在癫痫发作期间，棘波刻板性也得以维持。在癫痫发作期间，有一种增加半影放电的净趋势，尽管只有少数单位（10-20%）在基线期间显示出显著变化，值得注意的是，这些单位还包括放电显著减少的神经元。相比之下，在发作的核心领土内，以强烈的超同步多单元放电为特征的区域，我们的尖峰排序算法失败，因为单元被纳入癫痫发作活动。从那一刻起直到癫痫发作结束，不可能进行尖峰分选，但癫痫发作结束后尖峰形状的恢复很快：一些单位在癫痫发作结束后数十秒内重新出现，超过80%的单位在3分钟内重新出现（tau（recov）= 104 +/- 22 s）。在此时间范围内，平均放电率的恢复也接近发作前水平，这表明更持久的发作后状态不能用半影区或核心区的持续细胞神经生理功能障碍来解释。这些研究为未来研究这些记录如何告知临床实践奠定了基础。
Spike-sorting algorithms have been used to identify the firing patterns of isolated neurons ('single units') from implanted electrode recordings in patients undergoing assessment for epilepsy surgery, but we do not know their potential for providing helpful clinical information. It is important therefore to characterize both the stability of these recordings and also their context. A critical consideration is where the units are located with respect to the focus of the pathology. Recent analyses of neuronal spiking activity, recorded over extended spatial areas using microelectrode arrays, have demonstrated the importance of considering seizure activity in terms of two distinct spatial territories: the ictal core and penumbral territories. The pathological information in these two areas, however, is likely to be very different. We investigated, therefore, whether units could be followed reliably over prolonged periods of times in these two areas, including during seizure epochs. We isolated unit recordings from several hundred neurons from four patients undergoing video-telemetry monitoring for surgical evaluation of focal neocortical epilepsies. Unit stability could last in excess of 40 h, and across multiple seizures. A key finding was that in the penumbra, spike stereotypy was maintained even during the seizure. There was a net tendency towards increased penumbral firing during the seizure, although only a minority of units (10-20%) showed significant changes over the baseline period, and notably, these also included neurons showing significant reductions in firing. In contrast, within the ictal core territories, regions characterized by intense hypersynchronous multi-unit firing, our spike sorting algorithms failed as the units were incorporated into the seizure activity. No spike sorting was possible from that moment until the end of the seizure, but recovery of the spike shape was rapid following seizure termination: some units reappeared within tens of seconds of the end of the seizure, and over 80% reappeared within 3 min (tau(recov) = 104 +/- 22 s). The recovery of the mean firing rate was close to pre-ictal levels also within this time frame, suggesting that the more protracted post-ictal state cannot be explained by persistent cellular neurophysiological dysfunction in either the penumbral or the core territories. These studies lay the foundation for future investigations of how these recordings may inform clinical practice.