Effects Of Horizontal Bilateral Eye Movements On Perception And Memory In EMDR

Eye movement desensitization and reprocessing(EMDR)therapy is an important clinical method for treating post-traumatic stress disorder.The core treatment procedure for EMDR is that the patients retrieve their traumatic memory while simultaneously performing bilateral eye movements.Extensive evidence has shown that the bilateral eye movement can effectively reduce trauma-related symptoms,but its working mechanism is largely unclear.On the one hand,traditional psychological models argue that bilateral eye movements occupy the limited cognitive resources,thereby interfering with the retrieval and representation of traumatic memories;on the other hand,increasing evidence suggests that bilateral eye movements can promote the processing and even transition of the simultaneously perceived or retrieved information.In order to investigate the working mechanism of bilateral eye movements in EMDR,the present study simulated the EMDR procedure in the laboratory.In two experiments,healthy subjects were instructed to perform continuous bilateral eye movements while retrieving short-term(Experiment 1)or long-term(Experiment 2)memories with EEG signals being recorded.Multivariate pattern analysis was used to investigate the strength of the neural representation of perceptual and memory information during bilateral eye movements.Experiment 1 found that although the bilateral eye movement occupied cognitive resources and reduced the ongoing working memory performance,it also enhanced the neural representation of simultaneously perceived perceptual information.Further analysis found that the enhancement of perceptual representation was derived mainly from the contribution of the occipital brain region.Furthermore,the enhanced neural representation correlated significantly with the behavioral performance,showing functional significance.Experiment 2 showed that bilateral eye movements enhanced not only perceptual but also long-term memory representations.The enhanced long-term memory representations were accompanied by increased contributions from the prefrontal parietal and occipital regions.Collectively,these findings suggest that the bilateral eye movement in EMDR does not merely function as a dual task to occupy cognitive resources.Based on the current research results,we speculate that bilateral eye movements in EMDR can alleviate traumatic symptoms by promoting information processing and transition.This hypothesis needs to be investigated and verified by subsequent research.