Centre for Cognitive and Neural Systems, University of Edinburgh, Edinburgh, United Kingdom.
Hippocampus. 2010 Oct;20(10):1139-53. doi: 10.1002/hipo.20714.
The hippocampus is thought to be required for the associative recognition of objects together with the spatial or temporal contexts in which they occur. However, recent data showing that rats with fornix lesions perform as well as controls in an object-place task, while being impaired on an object-place-context task (Eacott and Norman (2004) J Neurosci 24:1948-1953), suggest that not all forms of context-dependent associative recognition depend on the integrity of the hippocampus. To examine the role of the hippocampus in context-dependent recognition directly, the present study tested the effects of large, selective, bilateral hippocampus lesions in rats on performance of a series of spontaneous recognition memory tasks: object recognition, object-place recognition, object-context recognition and object-place-context recognition. Consistent with the effects of fornix lesions, animals with hippocampus lesions were impaired only on the object-place-context task. These data confirm that not all forms of context-dependent associative recognition are mediated by the hippocampus. Subsequent experiments suggested that the object-place task does not require an allocentric representation of space, which could account for the lack of impairment following hippocampus lesions. Importantly, as the object-place-context task has similar spatial requirements, the selective deficit in object-place-context recognition suggests that this task requires hippocampus-dependent neural processes distinct from those required for allocentric spatial memory, or for object memory, object-place memory or object-context memory. Two possibilities are that object, place, and context information converge only in the hippocampus, or that recognition of integrated object-place-context information requires a hippocampus-dependent mode of retrieval, such as recollection.
海马体被认为是与物体一起发生的空间或时间上下文的联想识别所必需的。然而，最近的数据表明，穹窿切断的大鼠在物体-位置任务中的表现与对照组一样好，而在物体-位置-上下文任务中受损（Eacott 和 Norman（2004）J Neurosci 24：1948-1953），这表明并非所有形式的上下文相关联想识别都依赖于海马体的完整性。为了直接检查海马体在上下文相关识别中的作用，本研究测试了大鼠双侧海马体大选择性损伤对一系列自发识别记忆任务的影响：物体识别、物体-位置识别、物体-上下文识别和物体-位置-上下文识别。与穹窿切断的影响一致，海马体损伤的动物仅在物体-位置-上下文任务中受损。这些数据证实并非所有形式的上下文相关联想识别都由海马体介导。随后的实验表明，物体-位置任务不需要空间的无参照表征，这可以解释海马体损伤后缺乏损伤。重要的是，由于物体-位置-上下文任务具有相似的空间要求，因此物体-位置-上下文识别的选择性缺陷表明，该任务需要海马体依赖的神经过程不同于无参照空间记忆、物体记忆、物体-位置记忆或物体-上下文记忆所需的神经过程。有两种可能性：物体、位置和上下文信息仅在海马体中汇聚，或者整合的物体-位置-上下文信息的识别需要海马体依赖的检索模式，例如回忆。
