Brandão Marcus L, Zanoveli Janaína M, Ruiz-Martinez Raquel C, Oliveira Luciana C, Landeira-Fernandez Jesus
Instituto de Neurociências & Comportamento-INeC, Campus USP, 14040-901 Ribeirão Preto, SP, Brazil.
Behav Brain Res. 2008 Mar 17;188(1):1-13. doi: 10.1016/j.bbr.2007.10.018. Epub 2007 Oct 25.
Freezing defined as the complete absence of body movements is a normal response of animals to unavoidable fear stimuli. The present review presents a series of evidence relating different defensive patterns with specific anxiety disorders. There are at least four different kinds of freezing with specific neural substrates. The immobility induced by stimulation of the ventral column of the periaqueductal gray (vPAG) has been considered a quiescence characteristic of the recovery component of defense-recuperative processes. There is an isomorphism between freezing response to contextual stimuli paired with electrical shocks and generalized anxiety disorder. Besides, two types of freezing emerge with the electrical stimulation of the dorsal aspects of the periaqueductal gray (dPAG): the dPAG-evoked freezing and the dPAG post-stimulation freezing. Evidence is presented in support of the hypothesis that whereas dPAG-evoked freezing would serve as a model of panic attacks, the dPAG post-stimulation freezing appears to be a model of panic disorder. It is also proposed that conditioned freezing plus dPAG electrical stimulation might also mimic panic disorder with agoraphobia. A model of serotoninergic modulation through on- and off-cells of the defense reaction generated in the dPAG is also presented. The understanding of how the periaqueductal gray generates and elaborates different types of freezing is of relevance for our better knowledge of distinct types of anxiety such as panic disorder or generalized anxiety disorder.
僵住被定义为身体完全没有动作，是动物对不可避免的恐惧刺激的正常反应。本综述展示了一系列将不同防御模式与特定焦虑症相关联的证据。至少有四种不同类型的僵住，它们具有特定的神经基质。由中脑导水管周围灰质腹侧柱（vPAG）刺激诱发的不动被认为是防御恢复过程中恢复成分的静止特征。对与电击配对的情境刺激的僵住反应和广泛性焦虑症之间存在同构关系。此外，中脑导水管周围灰质背侧（dPAG）的电刺激会出现两种类型的僵住：dPAG诱发的僵住和dPAG刺激后的僵住。有证据支持这样的假设，即dPAG诱发的僵住可作为惊恐发作的模型，而dPAG刺激后的僵住似乎是惊恐障碍的模型。还提出条件性僵住加上dPAG电刺激也可能模拟伴有广场恐惧症的惊恐障碍。还展示了一种通过dPAG中产生的防御反应的开细胞和关细胞进行5-羟色胺能调节的模型。理解中脑导水管周围灰质如何产生和阐述不同类型的僵住，对于我们更好地了解惊恐障碍或广泛性焦虑症等不同类型的焦虑症具有重要意义。
