McHugh Stephen B, Niewoehner Burkhard, Rawlins J N P, Bannerman David M
Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK.
Behav Brain Res. 2008 Jan 10;186(1):41-7. doi: 10.1016/j.bbr.2007.07.021. Epub 2007 Jul 21.
Previous lesion studies have suggested a functional dissociation along the septotemporal axis of the hippocampus. Whereas the dorsal hippocampus has been implicated in spatial memory processes, the ventral hippocampus may play a role in anxiety. However, these lesion studies are potentially confounded by demyelination of fibres passing through the lesion site, and the possibility of secondary, downstream changes in associated brain structures as a consequence of their chronic denervation following the lesion. In the present study, we have used the microinfusion of muscimol to temporarily inactivate either the dorsal or ventral hippocampus in order to re-examine the contribution of the hippocampal sub-regions to spatial memory. Microinfusion studies spare fibres of passage and offer fewer opportunities for compensatory changes because the effects are transient and short-lasting. Rats were infused prior to spatial working memory testing on a non-matching to place T-maze alternation task. Spatial working memory was impaired by dorsal but not ventral hippocampal inactivation. In a second experiment, infusion of the NMDAR antagonist, D-AP5, into dorsal hippocampus also impaired spatial working memory performance, suggesting that NMDAR function within the dorsal hippocampus makes an essential contribution to this aspect of hippocampal information processing.
以往的损伤研究表明，海马体沿隔颞轴存在功能分离。背侧海马体与空间记忆过程有关，而腹侧海马体可能在焦虑中起作用。然而，这些损伤研究可能因穿过损伤部位的纤维脱髓鞘以及损伤后相关脑结构因长期去神经支配而发生继发性下游变化的可能性而受到混淆。在本研究中，我们使用微量注射蝇蕈醇来暂时使背侧或腹侧海马体失活，以便重新审视海马体亚区域对空间记忆的贡献。微量注射研究不会损伤通过的纤维，并且由于效应是短暂的，所以产生代偿性变化的机会较少。在对大鼠进行位置不匹配的T迷宫交替任务的空间工作记忆测试之前，对其进行微量注射。背侧海马体失活会损害空间工作记忆，而腹侧海马体失活则不会。在第二个实验中，向背侧海马体注射NMDAR拮抗剂D-AP5也会损害空间工作记忆表现，这表明背侧海马体内的NMDAR功能对海马体信息处理的这一方面做出了重要贡献。
