The importance of the hippocampus in spatial learning is well established, but the precise relative contributions by the dorsal (septal) and ventral (temporal) subregions remain unresolved. One debate revolves around the extent to which the ventral hippocampus contributes to spatial navigation and learning. Here, separate small subtotal lesions of dorsal hippocampus or ventral hippocampus alone (destroying 18.9 and 28.5% of total hippocampal volume, respectively) spared reference memory acquisition in the water maze. By contrast, combining the two subtotal lesions significantly reduced the rate of acquisition across days. This constitutes evidence for synergistic integration between dorsal and ventral hippocampus in mice. Evidence that ventral hippocampus contributes to spatial/navigation learning also emerged early on during the retention probe test as search preference was reduced in mice with ventral lesions alone or combined lesions. The small ventral lesions also led to anxiolysis in the elevated plus maze and over‐generalization of the conditioned freezing response to a neutral context. Similar effects of comparable magnitudes were seen in mice with combined lesions, suggesting that they were largely due to the small ventral damage. By contrast, small dorsal lesions were uniquely associated with a severe spatial working memory deficit in the water maze. Taken together, both dorsal and ventral poles of the hippocampus contribute to efficient spatial navigation in mice: While the integrity of dorsal hippocampus is necessary for spatial working memory, the acquisition and retrieval of spatial reference memory are modulated by the ventral hippocampus. Although the impairments following ventral damage (alone or in combination with dorsal damage) were less substantial, a wider spectrum of spatial learning, including context conditioning, was implicated. Our results encourage the search for integrative mechanism between dorsal and ventral hippocampus in spatial learning. Candidate neural substrates may include dorsoventral longitudinal connections and reciprocal modulation via overlapping polysynaptic networks beyond hippocampus.

中文翻译：

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背侧或腹侧海马亚区的小病变与工作记忆和参考记忆检索的明显障碍有关，将它们结合起来会降低空间参考记忆的获取率。

海马体在空间学习中的重要性已经确立，但背侧（中隔）和腹侧（颞侧）亚区域的精确相对贡献仍未解决。一场辩论围绕腹侧海马体对空间导航和学习的贡献程度展开。在这里，单独的背海马体或腹侧海马体的单独小次全病变（分别破坏海马总体积的 18.9% 和 28.5%）避免了水迷宫中的参考记忆获取。相比之下，结合两个小计病变显着降低了几天内的采集率。这构成了小鼠背侧和腹侧海马体协同整合的证据。腹侧海马体有助于空间/导航学习的证据也在保留探针测试的早期出现，因为在具有单独腹侧病变或合并病变的小鼠中搜索偏好降低。小的腹侧病变还导致高架十字迷宫中的焦虑症和对中性环境的条件冻结反应的过度概括。在合并病变的小鼠中也观察到了类似的影响，这表明它们主要是由于腹侧的小损伤。相比之下，小的背部病变与水迷宫中严重的空间工作记忆缺陷有关。综上所述，海马体的背侧极和腹侧极有助于小鼠的有效空间导航：虽然背海马体的完整性对于空间工作记忆是必要的，空间参考记忆的获取和检索受腹侧海马体调节。尽管腹侧损伤（单独或与背侧损伤相结合）后的损伤不那么严重，但涉及更广泛的空间学习，包括情境条件反射。我们的结果鼓励在空间学习中寻找背侧和腹侧海马体之间的整合机制。候选神经基质可能包括背腹纵向连接和通过海马体以外重叠多突触网络的相互调制。包括上下文条件，都受到牵连。我们的结果鼓励在空间学习中寻找背侧和腹侧海马体之间的整合机制。候选神经基质可能包括背腹纵向连接和通过海马体以外重叠多突触网络的相互调制。包括上下文条件，都受到牵连。我们的结果鼓励在空间学习中寻找背侧和腹侧海马体之间的整合机制。候选神经基质可能包括背腹纵向连接和通过海马体以外重叠多突触网络的相互调制。