应用多电极记录技术研究海马切片癫痫样放电的起始点和传播方向

弄清癫痫样放电的起始位置和传播方向对研究癫痫机制及其临床治疗有重要意义．为了解决这一问题，应用微电极阵列对低镁人工脑脊液诱导的Sprague-Dawley (SD)大鼠海马切片的癫痫样放电进行记录．分别用癫痫样放电的两种成分：场电位和多单元信号来确定癫痫样放电的起始位置和传播方向．首先计算并比较了海马切片锥体细胞层位置电极记录的癫痫样放电场电位的起始时间，由起始时间的先后关系确定癫痫样放电在锥体细胞层的起始位置和传播方向．然后用整个切片上记录的癫痫样放电的多单元信号动作电位序列进行互相关分析，进一步确定了癫痫样放电在整个海马切片内的起始位置和传播方向．结果显示，CA3区的癫痫样放电具有比CA1区更高的幅度和更长的持续时间，表明CA3区有更高的兴奋性．对于记录到的同步癫痫样放电，CA3b区场电位和多单元信号均比CA3c和CA1区出现更早，起始位置和其随后位置之间的传播延　时与二者之间的距离成正相关．因此，在低镁模型的大鼠海马切片中，癫痫样放电起始于CA3b区并分别向CA3c和CA1区传播．

Investigation of the initiation site and propagation of epileptiform discharges in hippocampal slices using microelectrode array

Understanding the initiation site and propagation of epileptiform discharges are of important significance for investigating the mechanisms of epilepsy and thereby for the clinically remedy. In order to solve the above problems, epileptiform discharges induced by low-Mg2+ artificial cerebrospinal fluid (ACSF) in Sprague- Dawley (SD) rat hippocampal slices were recorded by microelectrode array. Two components of epileptiform discharges: field potentials and multiple unit activity (MUA) were analyzed. Firstly, the onset time of field potentials in stratum pyramidale was calculated and compared to locate the initiation site and propagation of epileptiform discharges. Then cross-correlation analysis was applied to spike trains of MUA. Time delays obtained from cross-correlation function further confirmed the initiation site and propagation of epileptiform discharges in the whole hippocampal slice. The results revealed that epileptiform discharges in CA3 had larger amplitudes and longer duration than that in CA1, which indicated more excitability in CA3. Field potentials as well as MUA in CA3b occurred earlier compared with the synchronous signals in CA3c and CA1. The time delays between the onset and its following areas were positive relative to the distances between them. The result demonstrated that in low-Mg²⁺ ACSF-perfused SD rat hippocampal slice, epileptiform discharges originated from CA3b and propagated to CA3c and CA1 region respectively.