Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, The University of Lethbridge, Alberta T1K 3M4, Canada.
Eur J Neurosci. 2011 Sep;34(5):780-6. doi: 10.1111/j.1460-9568.2011.07796.x.
Context memories normally depend on the hippocampus (HPC) but, in the absence of the HPC, other memory systems are capable of acquiring and supporting these memories. This suggests that the HPC can interfere with other systems during memory acquisition. Here we ask whether the HPC can also interfere with the retrieval of a context memory that was independently acquired by a non-HPC system. Specifically, we assess whether the HPC can impair the retrieval of a contextual fear-conditioning memory that was acquired while the HPC was temporarily inactive. Rats were infused with the γ-aminobutyric acid (GABA)(A) receptor agonist muscimol in the dorsal and ventral HPC either before acquisition, retrieval, or prior to both acquisition and retrieval, consistent with the effects of permanent HPC lesions on contextual fear conditioning, if the HPC was inactive at the time of acquisition and retention memory was intact. Thus, non-HPC systems acquired and supported this memory in absence of the HPC. However, if the HPC was inactive during acquisition but active thereafter, rats displayed severe deficits during the retention test. Moreover, when the same rats received a second retention test but with the HPC inactive at this time, the memory was recovered, suggesting that removal of a form of interference allowed the memory to be expressed. Combined, these findings imply that the HPC competes and/or interferes with retrieval of a long-term memory that was established in non-HPC systems.
情景记忆通常依赖于海马体（HPC），但在没有 HPC 的情况下，其他记忆系统能够获取和支持这些记忆。这表明 HPC 在记忆获取过程中会干扰其他系统。在这里，我们想知道 HPC 是否也会干扰由非 HPC 系统独立获取的情景记忆的检索。具体来说，我们评估 HPC 是否会损害在 HPC 暂时失活时获取的情景性恐惧条件反射记忆的检索。在与永久性 HPC 损伤对情景性恐惧条件反射的影响一致的情况下，向大鼠的背侧和腹侧 HPC 中输注γ-氨基丁酸（GABA）（A）受体激动剂 muscimol，无论是在获取之前、检索之前还是在获取和检索之前，这会使情景性恐惧条件反射记忆保持完整。因此，非 HPC 系统在没有 HPC 的情况下获取并支持了这种记忆。然而，如果在获取期间 HPC 失活但随后又恢复了活动，那么大鼠在保留测试中会表现出严重的缺陷。此外，当相同的大鼠接受第二次保留测试，但此时 HPC 失活时，记忆得到了恢复，这表明消除了一种形式的干扰使记忆得以表达。综上所述，这些发现表明 HPC 会竞争和/或干扰由非 HPC 系统建立的长期记忆的检索。
