Clarifying the role of the rostral dmPFC/dACC in fear/anxiety: learning, appraisal or expression?
Clarifying the role of the rostral dmPFC/dACC in fear/anxiety: learning, appraisal or expression?
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DOI：
10.1371/journal.pone.0050120
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Tüscher O
中科院分区：
文献类型：
--
作者：
Maier S;Szalkowski A;Kamphausen S;Perlov E;Feige B;Blechert J;Philipsen A;van Elst LT;Kalisch R;Tüscher O
最近的研究已经开始发现背侧内侧前额叶皮质(DmPFC)的吻侧部分和邻近的背侧前扣带回(DACC)在恐惧/焦虑中的特定作用。在背侧mPFC/ACC区和腹侧mPFC/ACC区的一个新的一般框架内，dmPFC/dACC被提出专门调节对威胁情境的有意识的、消极的评估，作为极端变体，包括灾难性的威胁情境。另一种尚未被最终排除的解释是，该区域参与了恐惧学习。我们测试了两种不同的恐惧表达范式，分别对独立的健康成年受试者进行了fMRI研究(研究1：指示恐惧，研究2：巴甫洛夫条件性恐惧测试)。在这两种模式中，缺乏强化排除了条件反射。我们展示了一个相同的吻端dmPFC/dACC区域的显著大胆激活。在巴甫洛夫范式(研究2)中，该区域只有在先前的条件反射完成后才会强烈激活。因此，我们的数据反对该区域在恐惧学习中的作用。我们进一步重复了外周生理恐惧反应和嘴部dmPFC/dACC激活之间的分离的重复观察，强烈表明该区域并不直接产生恐惧反应，而是参与评估过程。尽管我们在这两种范式中都成功地阻止了条件性反应的消亡，但数据并不允许我们明确排除该区域参与恐惧消退学习的可能性。我们讨论了这一发现的更广泛的含义，以帮助我们理解mPFC/ACC在恐惧和更广泛的负面情绪中的作用。
Recent studies have begun to carve out a specific role for the rostral part of the dorsal medial prefrontal cortex (dmPFC) and adjacent dorsal anterior cingulate cortex (dACC) in fear/anxiety. Within a novel general framework of dorsal mPFC/ACC areas subserving the appraisal of threat and concomitant expression of fear responses and ventral mPFC/ACC areas subserving fear regulation, the rostral dmPFC/dACC has been proposed to specifically mediate the conscious, negative appraisal of threat situations including, as an extreme variant, catastrophizing. An alternative explanation that has not been conclusively ruled out yet is that the area is involved in fear learning. We tested two different fear expression paradigms in separate fMRI studies (study 1: instructed fear, study 2: testing of Pavlovian conditioned fear) with independent groups of healthy adult subjects. In both paradigms the absence of reinforcement precluded conditioning. We demonstrate significant BOLD activation of an identical rostral dmPFC/dACC area. In the Pavlovian paradigm (study 2), the area only activated robustly once prior conditioning had finished. Thus, our data argue against a role of the area in fear learning. We further replicate a repeated observation of a dissociation between peripheral-physiological fear responding and rostral dmPFC/dACC activation, strongly suggesting the area does not directly generate fear responses but rather contributes to appraisal processes. Although we succeeded in preventing extinction of conditioned responding in either paradigm, the data do not allow us to definitively exclude an involvement of the area in fear extinction learning. We discuss the broader implications of this finding for our understanding of mPFC/ACC function in fear and in negative emotion more generally.