Moderate Excitation Leads to Weakening of Perceptual Representations
Moderate Excitation Leads to Weakening of Perceptual Representations
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DOI：
10.1093/cercor/bhq021
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发表时间：
2010-11-01
期刊：
影响因子：
3.7
通讯作者：
Norman, Kenneth A.
中科院分区：
文献类型：
--
作者：
Newman, Ehren L.;Norman, Kenneth A.
记忆研究的一个基本目标是确定导致神经表征增强和减弱的条件。几个记忆形成的计算模型预测，学习效果应该作为神经表征所接收的兴奋量的非单调函数而变化。具体而言，适度的兴奋应导致突触减弱，而强烈的兴奋应导致突触加强。在啮齿类动物的可塑性的体外调查提供了支持，这一预测在单突触的水平。然而，目前还不清楚这一原则是否超越了突触到皮层表征，并表现出行为的变化。为了解决这个问题，我们在人类受试者中使用脑电图模式分类来测量刺激处理中的逐个试验波动，并且我们使用负启动范式来测量学习效果。与适度兴奋会导致减弱的观点一致，适度水平的刺激处理与负启动（随后对刺激的反应较慢）相关，但较高和较低水平的刺激处理与负启动无关。这些结果表明，导致啮齿类动物突触弱化的相同原理也可以解释人类感知表征的可及性降低。
A fundamental goal of memory research is to specify the conditions that lead to the strengthening and weakening of neural representations. Several computational models of memory formation predict that learning effects should vary as a nonmonotonic function of the amount of excitation received by a neural representation. Specifically, moderate excitation should result in synaptic weakening, while strong excitation should result in synaptic strengthening. In vitro investigations of plasticity in rodents have provided support for this prediction at the level of single synapses. However, it remains unclear whether this principle scales beyond the synapse to cortical representations and manifests changes in behavior. To address this question, we used electroencephalogram pattern classification in human subjects to measure trial-by-trial fluctuations in stimulus processing, and we used a negative priming paradigm to measure learning effects. In keeping with the idea that moderate excitation leads to weakening, moderate levels of stimulus processing were associated with negative priming (slower subsequent responding to the stimulus), but higher and lower levels of stimulus processing were not associated with negative priming. These results suggest that the same principles that account for synaptic weakening in rodents can also account for diminished accessibility of perceptual representations in humans.