Brain activity associated with omission of an aversive event reveals the effects of fear learning and generalization
Brain activity associated with omission of an aversive event reveals the effects of fear learning and generalization
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DOI：
10.1016/j.nlm.2012.02.003
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发表时间：
2012-03-01
影响因子：
2.7
通讯作者：
LaBar, Kevin S.
中科院分区：
文献类型：
--
作者：
Dunsmoor, Joseph E.;LaBar, Kevin S.
在恐惧学习过程中，对即将到来的厌恶刺激的预期会增加防御行为。有趣的是，忽略厌恶刺激通常会在预期事件发生的时间产生另一种反应。这种忽略反应表明，受试者发现了预测和实际发生之间的不匹配，从而提供了认知预期的间接测量。在这里，我们使用功能磁共振成像，以调查是否遗漏相关的大脑活动反映了恐惧预期在学习和条件恐惧的泛化。在条件反射过程中，一张表达适量恐惧（条件刺激，CS+）的脸发出了一个厌恶性休克无条件刺激（US）的信号，而同一张脸的中性表情是未经强化的。在随后的概括测试中，受试者的脸表达更多或更少的恐惧强度比CS+。心理生理学结果显示，当忽略US时，学习期间皮肤电导反应（SCR）增加。省略相关的SCR也观察到在泛化测试中的偏移高，但不是低强度的面部表情。神经影像学结果显示，在学习过程中，在前扣带皮层，顶叶皮层，纹状体和纹状体的遗漏相关的神经活动。在概括测试中，这些相同的区域也显示出与高度表达恐惧面孔有关的遗漏反应。最后，对概括测试期间的遗漏反应进行回归分析，揭示了偏移相关的SCR与背内侧前额叶皮质和后顶叶皮质的神经活动之间的相关性。因此，收敛的心理生理和神经活动省略厌恶刺激提供了一个新的度量美国的期望，甚至广义的线索，没有以前的历史强化。(C)2012 Elsevier Inc. All rights reserved.
During fear learning, anticipation of an impending aversive stimulus increases defensive behaviors. Interestingly, omission of the aversive stimulus often produces another response around the time the event was expected. This omission response suggests that the subject detected a mismatch between what was predicted and what actually occurred, thereby providing an indirect measure of cognitive expectancy. Here, we used functional magnetic resonance imaging to investigate whether omission-related brain activity reflects fear expectancy during learning and generalization of conditioned fear. During conditioning, a face expressing a moderate amount of fear (conditioned stimulus, CS+) signaled delivery of an aversive shock unconditioned stimulus (US), whereas the same face with a neutral expression was unreinforced. In a subsequent generalization test, subjects were presented with faces expressing more or less fear intensity than the CS+. Psychophysiological results revealed an increase in the skin conductance response (SCR) during learning when the US was omitted. Omission-related SCRs were also observed during the generalization test following the offset of high- but not low-intensity face expressions. Neuroimaging results revealed omission-related neural activity during learning in the anterior cingulate cortex, parietal cortex, insula, and striatum. These same regions also showed omission-related responses during the generalization test following highly expressive fearful faces. Finally, regression analysis on omission responses during the generalization test revealed correlations in offset-related SCRs and neural activity in the dorsomedial prefrontal cortex and posterior parietal cortex. Thus, converging psychophysiological and neural activity upon omission of aversive stimulation provides a novel metric of US expectancy, even to generalized cues that had no prior history of reinforcement. (C) 2012 Elsevier Inc. All rights reserved.