Dissociable roles for hippocampal and amygdalar volume in human fear conditioning
Dissociable roles for hippocampal and amygdalar volume in human fear conditioning
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DOI：
10.1007/s00429-014-0807-8
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发表时间：
2015-09-01
影响因子：
3.1
通讯作者：
Nees, Frauke
中科院分区：
文献类型：
--
作者：
Cacciaglia, Raffaele;Pohlack, Sebastian T.;Nees, Frauke
恐惧条件反射是一个基本的学习过程，它涉及到前中性条件刺激（CS）与生物相关的厌恶非条件刺激（US）的关联。先前在脑损伤患者中进行的研究表明，自主恐惧反应的获得需要完整的杏仁核，而保留的海马体对于CS-US应急意识的发展是必要的。尽管这些数据得到了健康人功能性神经成像技术研究的支持，但将这些发现扩展到杏仁核和海马体形态学方面的尝试还缺失。在这里，我们测试了杏仁核和海马体积在决定恐惧条件反射中的自主反应和偶然性意识方面发挥可分离作用的假设。52名健康个体（平均年龄21.83岁）接受了高分辨率磁共振成像。在评估皮肤电导反应（SCRs）、CS-US偶发的主观评分以及情绪效价和感知唤醒时，我们使用了差异延迟恐惧条件反射范式。左侧杏仁核体积显著预测恐惧习得过程中scr差异的大小，但对权变学习没有影响。相反，双侧海马体积与偶发性评分显著相关，但与scr无关。此外，左杏仁核体积预测单独增强的CS的scr，而不是由美国引起的scr。我们的发现弥补了之前病变和功能成像研究之间的差距，表明杏仁核和海马体积不同地调节条件恐惧的习得。此外，我们的研究结果表明，这些边缘结构的形态已经在健康人的学习和记忆中起调节作用。
Fear conditioning is a basic learning process which involves the association of a formerly neutral conditioned stimulus (CS) with a biologically relevant aversive unconditioned stimulus (US). Previous studies conducted in brain-lesioned patients have shown that while the acquisition of autonomic fear responses requires an intact amygdala, a spared hippocampus is necessary for the development of the CS-US contingency awareness. Although these data have been supported by studies using functional neuroimaging techniques in healthy people, attempts to extend these findings to the morphological aspects of amygdala and hippocampus are missing. Here we tested the hypothesis that amygdalar and hippocampal volumes play dissociable roles in determining autonomic responses and contingency awareness during fear conditioning. Fifty-two healthy individuals (mean age 21.83) underwent high-resolution magnetic resonance imaging. We used a differential delay fear conditioning paradigm while assessing skin conductance responses (SCRs), subjective ratings of CS-US contingency, as well as emotional valence and perceived arousal. Left amygdalar volume significantly predicted the magnitude of differential SCRs during fear acquisition, but had no impact on contingency learning. Conversely, bilateral hippocampal volumes were significantly related to contingency ratings, but not to SCRs. Moreover, left amygdalar volume predicted SCRs to the reinforced CS alone, but not those elicited by the US. Our findings bridge the gap between previous lesion and functional imaging studies, by showing that amygdalar and hippocampal volumes differentially modulate the acquisition of conditioned fear. Further, our results reveal that the morphology of these limbic structures moderate learning and memory already in healthy persons.