Chronometry of amygdala response to affective stimuli

描述(由申请者提供)：进化适应性决定了威胁必须被快速检测到。对潜在危害的快速识别导致了一个相对快速的、自动的威胁检测系统，倾向于误报。鉴于杏仁核在恐惧和对显著刺激的反应中的作用已被充分证明，杏仁核被认为可能是快速检测潜在威胁的促进器。根据研究表明，特定恐惧症患者对恐惧症相关刺激的反应更快，Larson及其同事(2002)发现，与中性和其他负面刺激相比，特定恐惧症患者在与恐惧症相关的刺激中杏仁核激活更快，并且与非恐惧症患者对恐惧症相关刺激的反应相比。这些数据强调了需要考虑情绪的动态过程及其神经实例化，以更全面地描述健康和病理性的情感反应。虽然上述数据表明杏仁核的快速反应是定义恐惧症的潜在特征，但杏仁核反应的时间过程中的灵活性也可能是一个正常的、适应性的过程，因此在最初呈现显著的情感刺激时，杏仁核反应更快，为潜在的威胁做好准备。随着时间的推移和减少 威胁的可能性这一反应变慢了。为了验证杏仁核激活的计时方法相对于刺激的显著程度是灵活的这一想法，15名健康受试者将完成一项关于杏仁核在厌恶条件下的反应时间进程的fMRI研究。据推测，杏仁核反应在条件反射阶段的早期将比后期条件反射和消退期更快。此外，还将比较杏仁核活动在消退和条件性抑制这两种减弱对厌恶条件刺激反应的方法中的动态模式。因此，本研究的主要目的是进一步考察情绪体验的神经基础的动态过程，包括情感过程的神经实例化的时间过程和大小。

DESCRIPTION (provided by applicant): Evolutionary fitness dictates that threat must be detected quickly. Rapid identification of potential harm has resulted in a relatively rapid, automatic threat detection system with a bias toward false positives. Given its well-documented role in fear and responses to salient stimuli, the amygdala has been identified as a likely facilitator of rapid detection of potential threats. Following work indicating that specific phobics respond more rapidly to phobia-relevant stimuli, Larson and colleagues (2002) found more rapid amygdala activation among specific phobics during phobia-relevant compared to neutral and other negative stimuli, and compared to nonphobic's responses to phobia-relevant stimuli. These data underscore the need to consider the dynamic process of emotion and its neural instantiation to more fully characterize healthy and pathological affective responses. While the aforementioned data point to rapid amygdala responding as a potential characteristic defining phobic fear, it is also possible that flexibility in the time course of the amygdala response is a normal, adaptive process such that during initial presentations of salient affective stimuli the amygdala responds more rapidly to prepare for potential threat. Over time and decreasing likelihood of threat this response slows. To test the idea that the chronometry of amygdala activation is flexible with respect to stimulus salience, 15 healthy subjects will complete an fMRI investigation of the time course of amygdala responding during an aversive conditioning paradigm. It is hypothesized that amygdale responses will be more rapid early in the conditioning phase compared to late conditioning and extinction periods. In addition, the dynamic pattern of amygdala activity during two means of attenuating responses to aversively conditioned stimuli, extinction and conditioned inhibition, will be compared. Thus, the major aim of the proposed study is to further examine the dynamic process of the neural substrates of emotional experience, including both time course and magnitude of the neural instantiation of affective processes.