Holdstock J S, Mayes A R, Cezayirli E, Aggleton J P, Roberts N
Department of Clinical Neurology, University of Sheffield, UK.
Cortex. 1999 Sep;35(4):479-501. doi: 10.1016/s0010-9452(08)70814-1.
Two patients with medial temporal lobe damage, seven Korsakoff amnesics and fourteen healthy control subjects were tested on three conditions of a spatial memory test ('short delay', 'allocentric' and 'egocentric'). The task required subjects to recall the position of a single spot of light presented on a board after various delays. The 'short delay' condition tested memory over very short, unfilled intervals. The other two conditions used longer, filled delays. The allocentric condition required subjects to move to a different place around the board before recalling the position of the light. In the egocentric condition stimuli were presented in darkness, which eliminated allocentric cues. The Korsakoff amnesics were impaired at all delays of the short delay tasks, suggesting poor encoding. On the allocentric and egocentric tasks the Korsakoff amnesics showed a comparable impairment in the two conditions, which worsened with delay. This accelerated forgetting suggested that the Korsakoff amnesics also had impaired memory for allocentric and egocentric information. The patients with medial temporal lobe damage were unimpaired in the 'short delay' condition suggesting intact encoding and short-term memory of spatial information. However, they were impaired in the allocentric condition and showed accelerated loss of allocentric spatial information. In the egocentric condition, while the performance of one patient was impaired, the performance of the other was as good as controls. This result suggests that, in contrast to allocentric spatial memory, which is sensitive to medial temporal lobe damage, an intact medial temporal lobe need not be necessary for successful performance on an egocentric spatial memory task.
两名患有内侧颞叶损伤的患者、七名柯萨科夫失忆症患者和十四名健康对照者在空间记忆测试的三种条件下(“短延迟”、“以自我为中心”和“以环境为中心”)接受了测试。该任务要求受试者在经过不同延迟后回忆出呈现在板上的单个亮点的位置。“短延迟”条件测试的是在非常短的、无填充间隔时间内的记忆。另外两种条件使用的是更长的、有填充的延迟时间。以环境为中心的条件要求受试者在回忆灯光位置之前移动到板周围的不同位置。在以自我为中心的条件下,刺激是在黑暗中呈现的,这消除了以环境为中心的线索。柯萨科夫失忆症患者在短延迟任务的所有延迟时间下都表现受损,表明编码能力较差。在以环境为中心和以自我为中心的任务中,柯萨科夫失忆症患者在这两种条件下表现出类似的损伤,且随着延迟时间的增加而恶化。这种加速遗忘表明柯萨科夫失忆症患者对于以环境为中心和以自我为中心的信息的记忆也受损。患有内侧颞叶损伤的患者在“短延迟”条件下未受损,表明空间信息的编码和短期记忆完好。然而,他们在以环境为中心的条件下表现受损,并且以环境为中心的空间信息出现加速丢失。在以自我为中心的条件下,一名患者的表现受损,而另一名患者的表现与对照组一样好。这一结果表明,与对内侧颞叶损伤敏感的以环境为中心的空间记忆不同,对于以自我为中心的空间记忆任务的成功完成,完整的内侧颞叶并非必要条件。