情景变换诱发已消退恐惧记忆重现的神经环路

Neural Circuits of the Relapse of Extinguished Fear Memory Induced by Changed Contexts

暴露疗法是治疗创伤后应激障碍的主要行为疗法。当被试反复暴露于可引起恐惧反应的条件刺激(如白噪音),但却不伴有非条件刺激(如足底电击)时,恐惧记忆将被消退,形成消退记忆。但恐惧记忆并未从根本上被擦除,当被试在消退训练以外的情景暴露于条件刺激时,已消退的恐惧记忆将会重现。海马、内侧前额叶皮层、杏仁核等脑区及其相互连接的神经环路是情景诱发恐惧记忆重现的生理基础。情景变化诱发恐惧记忆重现过程中,海马可能是通过直接投射至杏仁核基底核、杏仁核外侧核或通过边缘前皮质间接调控杏仁核基底核、杏仁核外侧核的功能,产生恐惧反应。

Exposure therapy is a type of cognitive behavioral therapy used for treatment of post-traumatic stress disorder. Using the cognitive behavioral therapy, the fear memory can be extinguished if the subjects are repeatedly exposed to a conditioned stimulus in absence of an unconditioned stimulus. However, the fear memory is not completely erased and tends to relapse in some conditions. Fear renewal is a typical model of fear relapse, which is induced when subjects are exposed to contexts outside of the extinction training. The hippocampus, medial prefrontal cortex and amygdala are critical brain regions involved in fear renewal and the connections and circuitries between these brain areas are also crucial physiological bases for fear renewal. The hippocampus regulates the amygdala activity by its direct projection to the basal amygdala or by its indirect projection via the prelimbic cortex in the renewal.