Quirk Gregory J, Garcia René, González-Lima Francisco
Department of Physiology, Ponce School of Medicine, Ponce, Puerto Rico.
Biol Psychiatry. 2006 Aug 15;60(4):337-43. doi: 10.1016/j.biopsych.2006.03.010. Epub 2006 May 19.
Interest in the medial prefrontal cortex (mPFC) as a source of behavioral inhibition has increased with the mounting evidence for a functional role of the mPFC in extinction of conditioned fear. In fear extinction, a tone-conditioned stimulus (CS) previously paired with a footshock is presented repeatedly in the absence of footshock, causing fear responses to diminish. Here, we review converging evidence from different laboratories implicating the mPFC in memory circuits for fear extinction: (1) lesions of mPFC impair recall of extinction under various conditions, (2) extinction potentiates mPFC physiological responses to the CS, (3) mPFC potentiation is correlated with extinction behavior, and (4) stimulation of mPFC strengthens extinction memory. These findings support Pavlov's original notion that extinction is new learning, rather than erasure of conditioning. In people suffering from posttraumatic stress disorder (PTSD), homologous areas of ventral mPFC show morphological and functional abnormalities, suggesting that extinction circuits are compromised in PTSD. Strategies for augmenting prefrontal function for clinical benefit are discussed.
随着内侧前额叶皮质（mPFC）在条件性恐惧消退中发挥功能作用的证据越来越多，人们对其作为行为抑制源的兴趣也日益增加。在恐惧消退过程中，先前与足部电击配对的音调条件刺激（CS）在没有足部电击的情况下反复呈现，导致恐惧反应减弱。在这里，我们回顾了来自不同实验室的越来越多的证据，这些证据表明mPFC参与了恐惧消退的记忆回路：（1）mPFC损伤会损害在各种条件下的消退记忆，（2）消退会增强mPFC对CS的生理反应，（3）mPFC增强与消退行为相关，（4）刺激mPFC会加强消退记忆。这些发现支持了巴甫洛夫最初的观点，即消退是新的学习，而不是对条件作用的消除。在患有创伤后应激障碍（PTSD）的人中，腹侧mPFC的同源区域表现出形态和功能异常，这表明PTSD中的消退回路受到了损害。文中还讨论了增强前额叶功能以获得临床益处的策略。
