Braem Senne, De Houwer Jan, Demanet Jelle, Yuen Kenneth S L, Kalisch Raffael, Brass Marcel
Department of Experimental Psychology and
Department of Experimental Clinical and Health Psychology, Ghent University, 9000 Ghent, Belgium, and.
J Neurosci. 2017 Aug 23;37(34):8116-8130. doi: 10.1523/JNEUROSCI.0908-17.2017. Epub 2017 Jul 21.
Learning fear via the experience of contingencies between a conditioned stimulus (CS) and an aversive unconditioned stimulus (US) is often assumed to be fundamentally different from learning fear via instructions. An open question is whether fear-related brain areas respond differently to experienced CS-US contingencies than to merely instructed CS-US contingencies. Here, we contrasted two experimental conditions where subjects were instructed to expect the same CS-US contingencies while only one condition was characterized by prior experience with the CS-US contingency. Using multivoxel pattern analysis of fMRI data, we found CS-related neural activation patterns in the right amygdala (but not in other fear-related regions) that dissociated between whether a CS-US contingency had been instructed and experienced versus merely instructed. A second experiment further corroborated this finding by showing a category-independent neural response to instructed and experienced, but not merely instructed, CS presentations in the human right amygdala. Together, these findings are in line with previous studies showing that verbal fear instructions have a strong impact on both brain and behavior. However, even in the face of fear instructions, the human right amygdala still shows a separable neural pattern response to experience-based fear contingencies. In our study, we addressed a fundamental problem of the science of human fear learning and memory, namely whether fear learning via experience in humans relies on a neural pathway that can be separated from fear learning via verbal information. Using two new procedures and recent advances in the analysis of brain imaging data, we localized purely experience-based fear processing and memory in the right amygdala, thereby making a direct link between human and animal research.
通常认为，通过条件刺激（CS）与厌恶非条件刺激（US）之间的意外事件体验来学习恐惧，与通过指令学习恐惧在本质上是不同的。一个悬而未决的问题是，与恐惧相关的脑区对经历过的CS-US意外事件的反应，是否与仅仅被告知的CS-US意外事件不同。在这里，我们对比了两种实验条件，在这两种条件下，受试者被指示预期相同的CS-US意外事件，而只有一种条件的特征是之前有过CS-US意外事件的经历。通过对功能磁共振成像（fMRI）数据进行多体素模式分析，我们发现右侧杏仁核（而非其他与恐惧相关的区域）中与CS相关的神经激活模式，在CS-US意外事件是被指示和经历过的还是仅仅被指示的情况下有所不同。第二个实验进一步证实了这一发现，该实验表明，在人类右侧杏仁核中，对被指示和经历过的（而非仅仅被指示的）CS呈现存在一种与类别无关的神经反应。总的来说，这些发现与之前的研究一致，这些研究表明言语恐惧指令对大脑和行为都有强烈影响。然而，即使面对恐惧指令，人类右侧杏仁核仍然对基于经验的恐惧意外事件表现出可分离的神经模式反应。在我们的研究中，我们解决了人类恐惧学习与记忆科学中的一个基本问题，即人类通过经验进行的恐惧学习是否依赖于一条可以与通过言语信息进行的恐惧学习相分离的神经通路。通过使用两种新方法以及脑成像数据分析的最新进展，我们将纯粹基于经验的恐惧处理和记忆定位到了右侧杏仁核，从而在人类和动物研究之间建立了直接联系。
