Bilateral interconnections through the hippocampal commissure play important roles in synchronizing or spreading hippocampal seizure activities. Intact hippocampi or bilateral hippocampal slices have been isolated from neonatal or immature rats (6–7 or 12–21 days old, respectively) and the mechanisms underlying the bilateral synchrony of hippocampal epileptiform activities have been investigated. However, the feasibility of examining bilateral epileptiform activities of more developed hippocampal circuitry in vitro remains to be explored. For this, we prepared bilateral hippocampal slices from C57 black mice, a strain commonly used in neuroscience and for genetic/molecular modifications. Young mice (21–24-day-old) were used in most experiments. A 600-μm-thick slice was obtained from each mouse by horizontal vibratome sectioning. Bilateral dorsal hippocampal and connecting dorsal hippocampal commissure (DHC) tissues were preserved in the slice and extrahippocampal tissues were removed. Slices were recorded in a submerged chamber mainly at a room temperature (21–22°C). Bilateral CA3 areas were monitored by extracellular recordings, and unilateral electrical stimulation was used to elicit CA3 synaptic field potentials. The unilateral stimulation could elicit population spikes in the contralateral CA3 area. These contralateral spikes were attenuated by inhibiting synaptic transmission with cobalt-containing medium and were abolished when a cut was made at the DHC. Self-sustained and bilaterally correlated epileptiform potentials were observed following application of 4-aminopyradine and became independent after the DHC cut. Bilateral hippocampal activities were detectable in some slices of adult mice and/or at 35–36°C, but with smaller amplitudes and variable waveforms compared to those observed from slices of young mice and at the room temperature. Together, these observations suggested that examining bilateral epileptiform activities in hippocampal slices of young mice is feasible. The weaknesses and limitations of this preparation and our experimentation are discussed.

通过海马连合的双边互连在同步或传播海马癫痫发作活动中起重要作用。已从新生或未成熟大鼠（分别为6-7岁或12-21天大）分离出完整的海马或双侧海马切片，并研究了海马癫痫样活动的双侧同步机制。但是，检查更发达的海马回路的双侧癫痫样活动的可行性体外有待探索。为此，我们从C57黑小鼠制备了双侧海马切片，C57黑小鼠是神经科学中常用的一种用于遗传/分子修饰的菌株。在大多数实验中使用了幼鼠（21-24天大）。通过水平振动刀切片从每只小鼠获得600μm厚的切片。切片中保留双侧背侧海马和连接背侧海马连合（DHC）组织，并去除海马外组织。切片记录在浸没室内，主要在室温（21–22°C）下进行。通过细胞外记录监测双边CA3区域，并使用单侧电刺激诱发CA3突触场电位。单侧刺激可引起对侧CA3区域的种群高峰。这些对侧尖峰通过用含钴介质抑制突触传递而减弱，并且在DHC切割时被消除。施用4-氨基吡啶后观察到自我维持和双边相关的癫痫样电位，并在DHC切割后变得独立。在成年小鼠的某些切片中和/或在35–36°C时，可以检测到双边海马活动，但与在室温下从年轻小鼠切片中观察到的相比，其幅度和可变波形较小。在一起，这些观察结果表明，检查年轻小鼠海马切片中的双边癫痫样活动是可行的。讨论了这种制备方法和实验的弱点和局限性。