Neural Basis of the Effect of Eye Movement Desensitization and Reprocessing (EMDR) Therapy on Cognition in Patients With Post-Traumatic Stress Disorder

This study aimed to investigate the effects of a single session of Butterfly Tapping (BT), a self-administered form of alternating bilateral stimulation, on emotional reactivity and its neurophysiological correlates. 46 participants will be randomly assigned to an experimental (Exp) or control (Con) group. The Exp group performed a 15-minute session of BT. Emotional reactivity was assessed before and after the stimulation using a detection task with emotional visual stimuli, presented during electroencephalographic (EEG) recording. EEG analyses were conducted using the event-related potential (ERP) method, specifically focusing on the differential amplitude (negative minus neutral) of the Late Positive Potential (LPP), a centro-parietal component associated with sustained processing of emotionally salient stimuli. Results revealed a significant LPP reduction in the Exp group at T1 compared to T0, whereas no change emerged in the Con group. The topographical distribution of the modulation was predominantly central, consistent with models implicating the LPP in higher-order integrative and evaluative processes. These findings provide preliminary neurophysiological evidence that BT may reduce cortical reactivity to negative emotional stimuli in young clinical populations, supporting its potential as a simple and accessible strategy capable of modulating affective responsiveness.