Hamm Alfons O, Weike Almut I
Department of Biological and Clinical Psychology, University of Greifswald, Franz-Mehring-Str. 47, 17487 Greifswald, Germany.
Int J Psychophysiol. 2005 Jul;57(1):5-14. doi: 10.1016/j.ijpsycho.2005.01.006. Epub 2005 Apr 21.
In the current review article it is suggested that fear is a central emotional state that can be activated by external threat cues. The subcortical defensive system cannot only be activated by intrinsically aversive events but shows also strong plasticity enabling previously innocuous stimuli to get access to the fear system after they were paired with painful outcomes. On the other hand, aversive conditioning does not only result in the acquisition of a defensive disposition, the organism also learns on a pure cognitive level that one stimulus predicts the occurrence of another stimulus. It is suggested here that potentiation of the acoustic startle reflex is a rather specific measure for fear acquisition, while skin conductance discrimination indexes contingency learning. It is shown that the acquisition of fear-potentiated startle does not require cortical processing of the conditioned stimulus. Moreover, data indicate that conditioned startle potentiation is abolished in patients with unilateral lesions of the amygdala. Finally, conditioned startle potentiation can be obtained without contingency awareness, which on the other hand is necessary for skin conductance conditioning to occur. It is suggested that the learning of stimulus relations is mediated by the hippocampus and that conditioned startle potentiation is also mediated by the hippocampus in trace conditioning.
在当前这篇综述文章中，有人提出恐惧是一种核心情绪状态，可由外部威胁线索激活。皮层下防御系统不仅能被内在厌恶事件激活，还表现出很强的可塑性，使得先前无害的刺激在与痛苦结果配对后能够进入恐惧系统。另一方面，厌恶条件作用不仅导致获得一种防御性倾向，机体还在纯粹认知层面上学会一个刺激预示着另一个刺激的出现。这里有人提出，听觉惊吓反射的增强是恐惧获得的一种相当特异的指标，而皮肤电传导辨别指数反映的是偶然性学习。研究表明，恐惧增强惊吓的获得并不需要对条件刺激进行皮层加工。此外，数据表明杏仁核单侧损伤的患者中条件性惊吓增强消失。最后，在没有偶然性意识的情况下也能获得条件性惊吓增强，而另一方面，皮肤电传导条件作用的发生则需要偶然性意识。有人提出刺激关系的学习由海马体介导，并且在痕迹条件作用中条件性惊吓增强也由海马体介导。
