Elfman Kane W, Aly Mariam, Yonelinas Andrew P
Department of Psychology, University of California, Davis.
Hippocampus. 2014 Dec;24(12):1672-86. doi: 10.1002/hipo.22345. Epub 2014 Aug 27.
Recent evidence suggests that the hippocampus, a region critical for long-term memory, also supports certain forms of high-level visual perception. A seemingly paradoxical finding is that, unlike the thresholded hippocampal signals associated with memory, the hippocampus produces graded, strength-based signals in perception. This article tests a neurocomputational model of the hippocampus, based on the complementary learning systems framework, to determine if the same model can account for both memory and perception, and whether it produces the appropriate thresholded and strength-based signals in these two types of tasks. The simulations showed that the hippocampus, and most prominently the CA1 subfield, produced graded signals when required to discriminate between highly similar stimuli in a perception task, but generated thresholded patterns of activity in recognition memory. A threshold was observed in recognition memory because pattern completion occurred for only some trials and completely failed to occur for others; conversely, in perception, pattern completion always occurred because of the high degree of item similarity. These results offer a neurocomputational account of the distinct hippocampal signals associated with perception and memory, and are broadly consistent with proposals that CA1 functions as a comparator of expected versus perceived events. We conclude that the hippocampal computations required for high-level perceptual discrimination are congruous with current neurocomputational models that account for recognition memory, and fit neatly into a broader description of the role of the hippocampus for the processing of complex relational information.
最近的证据表明，海马体作为对长期记忆至关重要的区域，也支持某些形式的高级视觉感知。一个看似矛盾的发现是，与和记忆相关的阈值化海马体信号不同，海马体在感知过程中产生基于强度分级的信号。本文测试了基于互补学习系统框架的海马体神经计算模型，以确定同一模型是否能解释记忆和感知，以及它在这两种类型的任务中是否产生适当的阈值化信号和基于强度的信号。模拟结果表明，在感知任务中，当需要区分高度相似的刺激时，海马体，尤其是CA1子区域，会产生分级信号，但在识别记忆中会产生阈值化的活动模式。在识别记忆中观察到一个阈值，是因为模式完成仅在某些试验中发生，而在其他试验中完全不发生；相反，在感知中，由于项目的高度相似性，模式完成总是会发生。这些结果为与感知和记忆相关的不同海马体信号提供了一种神经计算解释，并且与CA1作为预期事件与感知事件比较器的提议大致一致。我们得出结论，高级感知辨别所需的海马体计算与解释识别记忆的当前神经计算模型是一致的，并且很好地契合了对海马体在处理复杂关系信息方面作用的更广泛描述。
