Department of Psychiatry, University Hospital of Muenster, Germany.
Psychol Med. 2011 Apr;41(4):789-98. doi: 10.1017/S0033291710001248. Epub 2010 Jun 16.
Fear conditioning involves the amygdala as the main neural structure for learning fear responses whereas fear extinction mainly activates the inhibitory prefrontal cortex (PFC). In this study we investigated whether individual differences in trait anxiety affect amygdala and dorsal anterior cingulate cortex (dACC) activation during fear conditioning and extinction.
Thirty-two healthy subjects were investigated by functional magnetic resonance imaging (fMRI) at 3 T while performing a cued fear-conditioning task. All participants completed the trait version of the State-Trait Anxiety Inventory (STAI-T). Activations of the amygdala and the dACC were examined with respect to the effects of trait anxiety.
Analysis of the fMRI data demonstrated enhanced activation in fear-related brain areas, such as the insula and the ACC, during both fear conditioning and extinction. Activation of the amygdala appeared only during the late acquisition phase whereas deactivation was observed during extinction. Regression analyses revealed that highly trait-anxious subjects exhibited sustained amygdala activation and reduced dACC involvement during the extinction of conditioned responses.
This study reveals that high levels of trait anxiety are associated with both increased amygdala activation and reduced dACC recruitment during the extinction of conditioned fear. This hyper-responsivity of the amygdala and the deficient cognitive control during the extinction of conditioned fear in anxious subjects reflect an increased resistance to extinct fear responses and may thereby enhance the vulnerability to developing anxiety disorders.
恐惧条件反射涉及杏仁核作为学习恐惧反应的主要神经结构，而恐惧消退主要激活抑制性前额叶皮层（PFC）。在这项研究中，我们调查了特质焦虑个体差异是否会影响恐惧条件反射和消退过程中杏仁核和背侧前扣带皮层（dACC）的激活。
32 名健康受试者在 3T 磁共振成像（fMRI）下进行了提示性恐惧条件反射任务。所有参与者都完成了状态特质焦虑量表（STAI-T）的特质部分。通过 fMRI 数据，检查了特质焦虑对杏仁核和 dACC 激活的影响。
fMRI 数据分析表明，在恐惧相关脑区（如岛叶和 ACC），无论是在恐惧条件反射还是消退过程中，都存在增强的激活。杏仁核的激活仅出现在后期获取阶段，而在消退过程中观察到去激活。回归分析表明，高特质焦虑的受试者在条件反射反应的消退过程中表现出持续的杏仁核激活和 dACC 参与减少。
本研究表明，高水平的特质焦虑与条件性恐惧消退过程中杏仁核的过度激活和 dACC 招募减少有关。在焦虑受试者中，这种杏仁核的过度反应和条件性恐惧消退过程中认知控制的不足反映了对消退恐惧反应的抵抗力增加，从而可能增强发展为焦虑障碍的易感性。
