Dynamics of defensive behavior and memory in the face of stress and approaching social threat: A multi-method approach

防御级联模型是一种研究适应性和非适应性防御行为的跨诊断方法(Fanselow，1994；Lang等人，1997)。最初起源于动物，最近也得到了人类研究的支持，研究表明，防御行为随着对威胁的日益接近而发生系统性的变化，这取决于可用的反应选项，如逃跑。这种防御行为的变化被概念化为三个防御阶段：遭遇前防御(先发制人的行为，包括当威胁可能但没有被检测到时的非特定警惕)，遭遇后防御(当检测到威胁时，专注地凝视和特定于威胁的注意)和大约打击(当威胁最迫在眉睫，需要逃跑行为，逃跑-逃跑反应)。计划项目的中心目标是首次将这种防御反应级联扩展到健康个人的社会威胁(概念验证)，并调查具有社交焦虑症状的个人防御反应动员的共同性和特殊性。为了识别防御反应的不同动态变化，我们将实施一种新的社会威胁情景(从中性表情到愤怒表情的动态变化)，在不同的反应选项(不可控的威胁和回避)下，使用多种外周生理(惊吓反射、心率、皮肤电导)和大脑测量(事件相关电位；稳态视觉诱发电位)，实施言语贬值(约-打击)。此外，由于之前的研究表明，压力会调节冻结、回避行为和记忆，该项目还将研究社会压力对防御行为、可用反应选项和记忆形成的调节作用，所有这些都可能是社交焦虑症状发展和维持的关键因素。这一项目的结果不仅将为应对日益临近的社会威胁时防御行为的适应动态提供新的见解，也将为理解社交焦虑中的防御行为提供重要的启示，这也可能导致更好的个性化治疗方案(例如，为了减少冻结和回避行为)。

The defense cascade model is a transdiagnostic approach to study adaptive and maladaptive defensive behaviors (Fanselow, 1994; Lang et al., 1997). Originally derived from animal and recently also supported in human studies it has been shown that defensive behaviors systematically change with increasing proximity of a threat, depending on available response options such as escape. This change in defensive behaviors has been conceptualized in three defensive stages: pre-encounter defense (preemptive behavior, including unspecific vigilance when threat is likely but not detected), post-encounter defense (attentive freezing and threat-specific attention, when threat is detected) and circa strike (when threat is most imminent and requires escape behavior, flight-flight response). The central aim of the planned project is to extend this cascade of defensive responses, for the first time, to social threats in healthy individuals (proof of concept) and to investigate the communalities but also specifics of defensive response mobilization in individuals with symptoms of social anxiety. To identify different dynamic changes of defensive reactivity we will implement a novel social threat scenario (dynamically changing faces from neutral to angry expressions) with verbal devaluation (circa-strike) under different response options (uncontrollable threat vs. avoidance) using multiple peripheral physiological (startle reflex, heart rate, skin conductance) and brain measures (event-related potentials, ERPs; steady-state visual evoked potentials, ssVEPs). Moreover, because previous studies indicate that stress mediates freezing, avoidance behavior and memory, the project will also study the modulatory role of social stress on defensive behaviors, available response options and memory formation, all of which may be critical factors in the development and maintenance of social anxiety symptoms. The outcome of this project will not only give new insights into the adaptive dynamics of defensive behavior in response to approaching social threat but also give important implications for understanding defensive behaviors in social anxiety, which may also lead to better personalized treatment protocols (e.g., in order to reduce freezing and avoidance behavior).