Lehmann Hugo, Lacanilao Samuel, Sutherland Robert J
Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, The University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada T1K 3M4.
Eur J Neurosci. 2007 Mar;25(5):1278-86. doi: 10.1111/j.1460-9568.2007.05374.x. Epub 2007 Mar 9.
We examined the effects of partial or complete damage to the hippocampus on long-term retention of a Pavlovian conditioned fear response to context. Rats received a single contextual fear-conditioning episode and 1 week, 3 months or 6 months later they received sham, partial (dorsal) or complete NMDA-induced damage of the hippocampus. During a retention test conducted 2 weeks after surgery, the control rats exhibited high levels of freezing in the context, although their level of freezing was significantly lower with longer retention intervals. Rats with complete hippocampal damage displayed very little freezing in the context at each learning-surgery interval. Partial hippocampal damage caused a smaller but consistent deficit in conditioned responding, especially at longer learning-surgery intervals. Neither group of hippocampus-damaged rats showed less retrograde amnesia for more remote memories. We found that the severity of retrograde amnesia for contextual fear conditioning following hippocampal damage is related to the extent of the damage and that there is consistent and severe retrograde amnesia for even remote contextual fear memories. These findings support the idea that the hippocampal formation has an essential and long-lasting, possibly permanent, role in memory for contexts.
我们研究了海马体部分或完全损伤对巴甫洛夫式条件性恐惧反应长期记忆的影响。大鼠接受单次情境恐惧条件训练，1周、3个月或6个月后，它们接受假手术、海马体部分（背侧）或完全NMDA诱导损伤。在手术后2周进行的记忆测试中，对照大鼠在该情境中表现出高水平的僵立，尽管随着记忆间隔时间延长，它们的僵立水平显著降低。在每个学习 - 手术间隔期，海马体完全损伤的大鼠在该情境中几乎没有僵立表现。海马体部分损伤导致条件反应出现较小但持续的缺陷，尤其是在较长的学习 - 手术间隔期。两组海马体损伤的大鼠对更久远记忆的逆行性遗忘均未减轻。我们发现，海马体损伤后情境恐惧条件反射逆行性遗忘的严重程度与损伤程度有关，即使是对久远的情境恐惧记忆也存在持续且严重的逆行性遗忘。这些发现支持了海马结构在情境记忆中具有重要且持久、可能是永久性作用的观点。
