Epilepsy is a common neurological disorder characterized by recurrent epileptic seizures. The cause of most cases of epilepsy is unknown. Although changes of calcium events in a single brain region during seizures have been reported before, there have been few studies on relations between calcium events of two different brain regions and epileptic behaviors in freely moving mice. To analyze calcium events simultaneously recorded in hippocampal CA1 (CA1) and primary motor cortex M1 (M1), and to explore their relations to various epileptic behaviors in freely moving epileptic models. Epileptic models were induced by Kainic acid (KA), a direct agonist of glutamatergic receptor, on adult male C57/BL6J mice. Calcium events of neurons and glia in CA1 and M1 labeled by a calcium indicator dye were recorded simultaneously with a multi-channel fiber photometry system. Three typical types of calcium events associated with KA-induced seizures were observed, including calcium baseline-rising, cortical spreading depression (CSD) and calcium flashing with a steady rate. Our results showed that the calcium baseline-rising occurred in CA1 was synchronized with that in M1, but the CSD waves were not. However, synchronization of calcium flashing in the two areas was uncertain, because it was only detected in CA1. We also observed that different calcium events happened with different epileptic behaviors. Baseline-rising events were accompanied by clonus of forelimbs or trembling, CSD waves were closely related to head movements (15 out of 18, 6 mice). Calcium flashing occurred definitely with drastic convulsive motor seizures (CMS, 6 mice). The results prove that the synchronization of calcium event exists in CA1 and M1, and different calcium events are related with different seizure behaviors. Our results suggest that calcium events involve in the synchronization of neural network and behaviors in epilepsy.

中文翻译：

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自由移动的癫痫小鼠海马CA1和初级运动皮层M1的同时钙记录及其与行为活动的关系。

癫痫病是一种常见的神经系统疾病，其特征是复发性癫痫发作。大多数癫痫病例的病因尚不清楚。尽管以前已经报道了癫痫发作期间单个大脑区域中钙事件的变化，但是很少有关于两个不同大脑区域的钙事件与自由移动小鼠的癫痫行为之间的关系的研究。要分析同时记录在海马CA1（CA1）和原发性运动皮层M1（M1）中的钙事件，并探讨它们与自由移动癫痫模型中各种癫痫行为的关系。由成年雄性C57 / BL6J小鼠的谷氨酸能受体直接激动剂海藻酸（KA）诱导产生癫痫模型。用多通道光纤测光系统同时记录了钙指示剂标记的CA1和M1中神经元和神经胶质的钙事件。观察到与KA诱发的癫痫发作有关的三种典型的钙事件，包括钙基线升高，皮层扩散抑制（CSD）和钙闪烁稳定。我们的结果表明，CA1中的钙基线升高与M1中的钙基线升高同步，但CSD波并不同步。但是，这两个区域中钙闪烁的同步性尚不确定，因为只能在CA1中检测到。我们还观察到不同的钙事件发生在不同的癫痫行为中。基线升高事件伴有前肢的阵挛或颤抖，CSD波与头部运动密切相关（18只小鼠中有15只，6只小鼠）。剧烈的惊厥性运动性癫痫发作（CMS，6只小鼠）肯定会发生钙闪烁。结果证明，钙离子事件在CA1和M1中存在同步，并且不同的钙离子事件与癫痫发作行为有关。我们的结果表明，钙事件参与了神经网络和癫痫行为的同步。