Epileptiform activity can be initiated in various neocortical layers: an optical imaging study.
Epileptiform activity can be initiated in various neocortical layers: an optical imaging study.
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DOI：
10.1152/jn.1999.82.4.1965
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发表时间：
1999-10
影响因子：
2.5
通讯作者：
Yang Tsau;Li Guan;Jian-Young Wu
中科院分区：
文献类型：
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作者：
Yang Tsau;Li Guan;Jian-Young Wu
触发癫痫样活动的起始位点进行了研究，通过光学成像使用电压敏感染料的新皮层切片灌注与人工脑脊髓液名义上含零镁。从Sprague-Dawley大鼠（P21-28）中收获新皮质切片（400 μ m厚）。通过使用高速光电二极管阵列进行光学成像。用零镁溶液灌注后20-40分钟出现自发性癫痫样活动。有一个很好的对应关系之间的电信号和光信号（n = 46），虽然两个记录的细节有些不同。在11个制剂的起始位点进行了光学测量。其中浅层4个，中层2个，深层5个。重复记录显示，这些起始位点相对稳定;未观察到起始位点的移位。因此，自发性癫痫样活动可以在各个皮层层，从I层到VI层启动。激活开始于小于0.04 mm（3）的小区域，并从起始部位平滑地扩散到相邻的皮质区域，这表明起始部位非常局限于其中一个皮质层。起始位点随机分布在不同的皮质区，没有发现在特定的皮质区有更高的概率。通过装有2 M NaCl（2-5 MOhms）的玻璃微电极传递的电刺激可以可靠地触发与自发活动具有相同特征的癫痫样活动。被刺激直接激活的皮层神经元位于电极尖端周围，估计在50微米的区域内，这表明只需要几个神经元就可以形成一个起始位点。由于刺激的时间是任意的，并且诱发事件的启动独立于任何其他层中的神经元的放电，因此在各个皮层层中癫痫样活动的起始位点很可能独立于第V层锥体神经元的控制。这些发现共同表明癫痫样病灶是局限的，可以在几个（可能是所有）新皮层层和许多皮层区域形成。起始神经元可能是不同类型的，因为不同皮质层中的神经元类型不同。
The initiation site for triggering epileptiform activity was investigated via optical imaging using voltage-sensitive dyes in the neocortical slice perfused with artificial cerebral spinal fluid containing nominally zero magnesium. The neocortical slices (400-microm thick) were harvested from Sprague-Dawley rats (P21-28). Optical imaging was made by using a high speed photodiode array. Spontaneous epileptiform activity emerged 20-40 min after the preparation was perfused with zero-magnesium solution. There was a good correspondence between electrical and optical signals (n = 46), although the details of the two recordings were somewhat different. The initiation sites were measured optically in 11 preparations. Among them, four were found to be located in superficial layers, two were found in middle layers, and five were found in deep layers. Repeated recordings revealed that these initiation sites were relatively stable; shifting of the initiation site was not observed. Therefore spontaneous epileptiform activity could be initiated in various cortical layers, from layer I to layer VI. The activation started from a small area <0.04 mm(3) and spread smoothly from the initiation site to adjacent cortical areas, suggesting that the initiation site is very confined to one of the cortical layers. The initiation sites were distributed randomly in various cortical areas, and no higher probability was found in a special cortical region. Electrical stimulation delivered via a glass microelectrode filled with 2 M NaCl (2-5 MOhms) could reliably trigger epileptiform activity that had the same characteristics as the spontaneous activity. The cortical neurons activated directly by the stimulation were around the electrode's tip and estimated to be within a 50-microm area, suggesting that only a few neurons were needed to form an initiation site. Because the timing for stimulation was arbitrary and the evoked events were initiated independent of discharges of neurons in any other layers, it is likely that the initiation site for epileptiform activity in various cortical layers is independent of the control of layer V pyramidal neurons. Together these finding suggest that the epileptiform focus is confined and can be formed in several (probably all) neocortical layers and in many cortical areas. The initiating neurons may be of different types because neuronal types in various cortical layers are different.