Neural Basis of the Effect of EMDR Therapy (EMDR-NEURO)

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.

Study Overview

• Status: Completed
• Conditions: PTSD - Post Traumatic Stress Disorder
• Intervention / Treatment: Behavioral: Butterfly Tapping (BT); Behavioral: No intervention control

• Study Type: Interventional
• Enrollment (Actual): 46
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Italy
  • RM
    • Rome, RM, Italy, 00135
      • University of Rome Foro Italico

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• normal or corrected-to-normal vision; full right-handedness

Exclusion Criteria:

• neurological or other psychiatric disorders tha PTSD; current use of psychoactive medications.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Butterfly Tapping; Participants assigned to the Experimental Group (Exp) will perform a self-administered session of Butterfly Tapping (BT), a form of alternating bilateral tactile stimulation widely used in Eye Movement Desensitization and Reprocessing (EMDR)-derived affect-regulation techniques. This arm was designed to test whether rhythmic bilateral sensory input modulates neural indices of emotional reactivity.	Behavioral: Butterfly Tapping (BT); Participants adopted the traditional butterfly hug posture: arms crossed over the chest, fingertips placed below the clavicles. They delivered alternating left-right rhythmic taps (~1 Hz) on their shoulders. Eyes remained closed, and participants were instructed to keep the emotional content active by mentally recalling previously viewed negative images, ensuring sustained affective engagement. Duration: 15 minutes, structured in four blocks of 3 minutes with short pauses. No auditory pacing was provided to preserve spontaneous rhythmicity. Targeted Mechanism Bilateral tactile stimulation aiming to modulate cortico-limbic processing, interhemispheric communication, and sustained emotional reactivity, as indexed by LPP amplitude during ta emotional simple response task; Other Names: Alternating Bilateral Stimulation
Sham Comparator: No tapping (Control Group); Participants assigned to the Control Group will maintain the same posture as the experimental group but will not perform any tapping. This static condition controls for posture, context, expectancy, and emotional activation, isolating the specific effect of the bilateral stimulation.	Behavioral: No intervention control; Participants will adopt the same butterfly-hug position, with arms crossed and hands placed on the chest. No rhythmic tapping or movements will be performed. Eyes are closed for the entire session, as in the experimental arm. Participants will held the emotional images in mind just as in the experimental arm. Duration: 15 minutes, identical block structure and timing as the BT condition. Targeted Mechanism Serves as a posture-matched and expectancy-matched control, ruling out effects of: simple stillness, emotional recall, attentional focus, physical posture, general relaxation effects.; Other Names: static position; Static Posture Control; No Alternating Stimulation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
LPP	Late Positive Potential (LPP) Differential Amplitude (Negative - Neutral) The primary neurophysiological outcome will be the modulation of the centro-parietal Late Positive Potential (LPP), extracted from EEG recordings during the Emotional Simple Response Task (E-SRT). The LPP is a well-established marker of sustained attentional and evaluative processing of emotional stimuli. For each participant and time point (T0, T1, T2), ERP waveforms willbe computed separately for negative and neutral images, and difference waves (negative minus neutral) were used to isolate emotion-specific neural reactivity. Primary analyses focused on mean amplitudes in the experimentally defined cLPP time window (456-552 ms) over the centro-parietal electrode cluster (Cz, C1, C2, CP1, CPz, CP2). The primary contrast of interest was the Group × Time interaction, assessing whether a single session of Butterfly Tapping selectively reduced the LPP differential amplitude relative to the static control condition.	Baseline, End of Treatment (8-12 weeks), and Follow-up (8 weeks after treatment completion)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Frontal positivity	Frontal Positivity (188-228 ms). Is sn exploratory secondary marker, indexing early evaluative or response-related processing, quantified over the frontal region (F1, Fz, F2, FC1, FCz, FC2).	Baseline, End of Treatment (8-12 weeks), and Follow-up (8 weeks after treatment completion)
Behavior	Behavioral Performance: Response Time (RT) to emotional images Omission Rate (OM) Both extracted from the E-SRT before and after stimulation.	Baseline, End of Treatment (8-12 weeks), and Follow-up (8 weeks after treatment completion)
Self-report	Self-Reported Emotional State: State Anxiety (STAI-Y1) Emotional Discomfort (VAS) Collected immediately after each task block to assess subjective affective changes.	Baseline, End of Treatment (8-12 weeks), and Follow-up (8 weeks after treatment completion)

Collaborators and Investigators

• Sponsor: University of Rome Foro Italico

Publications and helpful links

General Publications

• First MB. Diagnostic and statistical manual of mental disorders, 5th edition, and clinical utility. J Nerv Ment Dis. 2013 Sep;201(9):727-9. doi: 10.1097/NMD.0b013e3182a2168a. No abstract available.

Study record dates

Study Major Dates

• Study Start (Actual): January 8, 2025
• Primary Completion (Actual): July 30, 2025
• Study Completion (Actual): March 15, 2026

Study Registration Dates

• First Submitted: April 10, 2026
• First Submitted That Met QC Criteria: April 21, 2026
• First Posted (Actual): April 24, 2026

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 25, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: PTSD; EEG; emotion regulation; ERP; emotional reactivity; late positive potential; butterfly tapping
• Additional Relevant MeSH Terms: Trauma and Stressor Related Disorders; Mental Disorders; Stress Disorders, Traumatic; Behavior; Social Behavior; Self-Control; Stress Disorders, Post-Traumatic; Combat Disorders; Emotional Regulation
• Other Study ID Numbers: URomeForoItalico

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No