The functional organization of the hippocampus along its longitudinal (septotemporal or dorsoventral) axis is conspicuously heterogeneous. This functional diversification includes the activity of sharp wave and ripples (SPW–Rs), a complex intrinsic network pattern involved in memory consolidation. In this study, using transverse slices from the ventral and the dorsal rat hippocampus and recordings of CA1 field potentials we studied the development of SPW–Rs and possible changes in local network excitability and inhibition, during in vitro maintenance of the hippocampal tissue. We found that SPW–Rs develop gradually in terms of magnitude and rate of occurrence in the ventral hippocampus. On the contrary, neither the magnitude nor the rate of occurrence significantly changed in dorsal hippocampal slices during their in vitro maintenance. The development of SPW–Rs was accompanied by an increase in local network excitability more in the ventral than in the dorsal hippocampus, and an increase in local network inhibition in the ventral hippocampus only. Furthermore, the amplitude of SPWs positively correlated with the level of maximum excitation of the local neuronal network in both segments of the hippocampus, and the local network excitability and inhibition in the ventral but not the dorsal hippocampus. Blockade of α5 subunit-containing GABA_A receptor by L-655,708 significantly reduced the rate of occurrence of SPWs and enhanced the probability of their generation in the form of clusters in the ventral hippocampus without affecting activity in the dorsal hippocampus. The present evidence suggests that a dynamic upregulation of excitation and inhibition in the local neuronal network may significantly contribute to the generation of SPW–Rs, particularly in the ventral hippocampus.

海马沿其纵向（颞颞或背腹）轴的功能组织明显异质。这种功能多样化包括尖峰波和波纹（SPW–Rs）的活动，这是一种涉及内存整合的复杂内在网络模式。在这项研究中，使用大鼠腹侧和背侧海马的横切面以及记录CA1场电位，我们研究了SPW–Rs的发育以及体外过程中局部网络兴奋性和抑制作用的可能变化维持海马组织。我们发现SPW–Rs在腹侧海马区的大小和发生率方面逐渐发展。相反，在体外维持期间，海马背侧切片的大小和发生率均未发生明显变化。SPW-Rs的发展伴随着腹侧的局部网络兴奋性高于背侧海马，而腹侧海马仅局部网络兴奋性增加。此外，SPW的振幅与海马两段的局部神经元网络的最大兴奋程度以及腹侧而不是背侧海马中的局部网络兴奋性和抑制作用呈正相关。含α5亚基的GABA的阻断_阿由L-655708受体显著减少SPWS发生的速率和增强它们在腹侧海马簇的形式产生概率而不在背侧海马影响活性。目前的证据表明，局部神经元网络中兴奋和抑制的动态上调可能显着促进SPW-Rs的产生，特别是在腹侧海马中。