The Timing of Attentional Distraction Matters in Facilitating Extinction of Trace Fear Memory.

Eye movement desensitization and reprocessing (EMDR) is a popular psychotherapy used to alleviate mental distress associated with anxiety and trauma-related disorders. Although working memory taxation has been proposed as an underlying mechanism of the therapy, such claim yet remains controversial due to lack of neurobiological foundations and conflicting findings among studies. In this study, we distracted rats with flickering lights during their training of fear memory extinction. Temporal overlap of twenty-second visual stimulations with the anticipatory shock timing of trace fear conditioning effectively facilitated fear extinction in a subset of animals that showed relatively low freezing during the conditioning day, while random intermittent visual stimulations did not. Moreover, fear extinction in delay fear conditioned animals was not affected either by the same visual stimulations or the stimulations that overlapped with shock timing. These results show that attentional distraction facilitates trace fear extinction, and proper timing is a necessary condition for a sensory stimulation to effectively facilitate trace fear extinction. Implications of our findings in EMDR and potential neurobiological mechanisms are discussed.