Dolleman-van der Weel Margriet J, Morris Richard G M, Witter Menno P
Institute for Clinical and Experimental Neurosciences, Department of Anatomy and Neurosciences, VU University Medical Centre, Amsterdam, The Netherlands.
Brain Struct Funct. 2009 Feb;213(3):329-42. doi: 10.1007/s00429-008-0200-6. Epub 2009 Jan 9.
Rats with bilateral neurotoxic reuniens (RE), mediodorsal (MD), hippocampal (HIPP) or sham (SH) lesions were tested in a standard watermaze task, together with unoperated rats. RE-rats and SH-controls readily learned to swim directly to a hidden platform. In contrast, MD-rats displayed a transient deficit characterized initially by thigmotaxis. Like in previous studies, HIPP-rats had long latencies throughout training and displayed more random swims than the other groups. In a memory probe test with the platform removed, SH- and RE-rats approached the correct location relatively directly but, whereas SH-controls persistently searched in the training quadrant, RE-rats switched to searching all over the pool. The MD-group swam in loops to the platform, but then displayed persistent searching in the training quadrant. The HIPP-group performed at chance. These distinct patterns indicate that, although their search strategies were different, RE- and MD-rats had acquired sufficient knowledge about the platform location and could recall information in the probe test. All groups performed well in a subsequent cue test with a visible platform, with RE-rats initially escaping faster than the SH- and HIPP-groups, and MD-rats improving from an initially poorer level of performance to control level. This indicates that there were no sensorimotor or motivational deficits associated with any of the lesions. In conclusion, while the RE and MD nuclei seem not to be critical for the learning and memory of a standard watermaze task, they may contribute to non-mnemonic strategy shifting when animals are challenged in ways that do not occur during training.
对双侧神经毒性的连合核（RE）、背内侧核（MD）、海马体（HIPP）损伤或假手术（SH）的大鼠，与未手术的大鼠一起进行标准水迷宫任务测试。RE组大鼠和SH组对照大鼠很容易学会直接游向隐藏平台。相比之下，MD组大鼠表现出短暂的缺陷，最初表现为趋触性。与之前的研究一样，HIPP组大鼠在整个训练过程中潜伏期都很长，并且比其他组表现出更多的随机游动。在移除平台的记忆探测测试中，SH组和RE组大鼠相对直接地接近正确位置，但是，SH组对照大鼠持续在训练象限搜索，而RE组大鼠则转而在整个水池中搜索。MD组大鼠绕圈游向平台，但随后在训练象限持续搜索。HIPP组大鼠表现随机。这些不同的模式表明，尽管它们的搜索策略不同，但RE组和MD组大鼠已经获得了关于平台位置的足够知识，并且能够在探测测试中回忆信息。在随后的可见平台线索测试中，所有组表现良好，RE组大鼠最初逃脱的速度比SH组和HIPP组快，MD组大鼠从最初较差的表现水平提高到对照水平。这表明任何一种损伤都不存在感觉运动或动机缺陷。总之，虽然RE核和MD核似乎对标准水迷宫任务的学习和记忆不是至关重要的，但当动物受到训练期间未出现的方式的挑战时，它们可能有助于非记忆策略的转变。
