Degrading traumatic memories with eye movements: a pilot functional MRI study in PTSD

Eye movement desensitization and reprocessing (EMDR) is an effective treatment for posttraumatic stress disorder (PTSD). During EMDR, the patient recalls traumatic memories while making eye movements (EMs). Making EMs during recall is associated with decreased vividness and emotionality of traumatic memories, but the underlying mechanism has been unclear. Recent studies support a “working-memory” (WM) theory, which states that the two tasks (recall and EMs) compete for limited capacity of WM resources. However, prior research has mainly relied on self-report measures. Using functional magnetic resonance imaging, we tested whether “recall with EMs,” relative to a “recall-only” control condition, was associated with reduced activity of primary visual and emotional processing brain regions, associated with vividness and emotionality respectively, and increased activity of the dorsolateral prefrontal cortex (DLPFC), associated with working memory. We used a randomized, controlled, crossover experimental design in eight adult patients with a primary diagnosis of PTSD. A script-driven imagery (SDI) procedure was used to measure responsiveness to an audio-script depicting the participant's traumatic memory before and after conditions. SDI activated mainly emotional processing-related brain regions (anterior insula, rostral anterior cingulate cortex (ACC), and dorsomedial prefrontal cortex), WM-related (DLPFC), and visual (association) brain regions before both conditions. Although predicted pre- to post-test decrease in amygdala activation after “recall with EMs” was not significant, SDI activated less right amygdala and rostral ACC activity after “recall with EMs” compared to post-“recall-only.” Furthermore, functional connectivity from the right amygdala to the rostral ACC was decreased after “recall with EMs” compared with after “recall-only.” These preliminary results in a small sample suggest that making EMs during recall, which is part of the regular EMDR treatment protocol, might reduce activity and connectivity in emotional processing-related areas. This study warrants replication in a larger sample. Script driven imagery (SDI) before and after recall of traumatic memories is feasible to investigate working mechanisms of degrading of traumatic memories with eye movements (EMs) in PTSD. Right amygdala and rostral ACC activity was significantly lower after “recall with EMs” than after “recall-only”. Functional connectivity from amygdala to rostral ACC was decreased after “recall with EMs” vs. “recall-only”. This study warrants replication in a larger sample.

眼动脱敏与再加工（Eye movement desensitization and reprocessing, EMDR）是治疗创伤后应激障碍（posttraumatic stress disorder, PTSD）的有效疗法。在EMDR治疗过程中，患者会在进行眼动（eye movements, EMs）的同时回忆创伤性记忆。回忆过程中伴随眼动，与创伤性记忆的生动性及情绪唤起程度降低相关，但其背后的作用机制尚不明确。
近期研究支持“工作记忆”（working-memory, WM）理论，该理论提出，回忆创伤性记忆与进行眼动这两项任务会竞争有限的工作记忆资源。然而，此前的相关研究主要依赖自我报告式测量手段。
本研究借助功能磁共振成像（functional magnetic resonance imaging），相较于仅回忆的对照条件，检验“伴随眼动的回忆”是否与以下变化相关：分别与记忆生动性、情绪唤起相关的初级视觉皮层与情绪加工脑区的活动减弱，以及与工作记忆相关的背外侧前额叶皮层（dorsolateral prefrontal cortex, DLPFC）的活动增强。
本研究采用随机对照交叉实验设计，招募了8名确诊为PTSD的成年患者。
研究采用脚本驱动意象范式（script-driven imagery, SDI），用于测量被试在两种实验条件前后，对描述自身创伤性记忆的音频脚本的反应性。
在两种实验条件实施前，SDI主要激活了与情绪加工相关的脑区（前脑岛、喙侧前扣带回皮层（anterior cingulate cortex, ACC）以及背内侧前额叶皮层）、与工作记忆相关的脑区（DLPFC）以及视觉（联合）皮层。
尽管“伴随眼动的回忆”后杏仁核（amygdala）激活量的预测性测前-测后下降未达到显著水平，但相较于“仅回忆”条件后的测后结果，“伴随眼动的回忆”后右侧杏仁核与喙侧ACC的激活程度显著更低。
此外，相较于“仅回忆”条件后的测后结果，“伴随眼动的回忆”后右侧杏仁核到喙侧ACC的功能连接显著减弱。
这项基于小样本的初步研究结果表明，作为标准EMDR治疗流程组成部分的“回忆过程中伴随眼动”，或许能够降低情绪加工相关脑区的活动与功能连接强度。本研究有待在更大样本中进行重复验证。
在PTSD患者中，借助创伤性记忆回忆前后的脚本驱动意象范式，可有效探究眼动降低创伤性记忆强度的作用机制。
相较于“仅回忆”条件，“伴随眼动的回忆”后右侧杏仁核与喙侧ACC的活动水平显著更低。
“伴随眼动的回忆”后杏仁核到喙侧ACC的功能连接相较于“仅回忆”条件显著减弱。
本研究有待在更大样本中进行重复验证。