Understanding the Neuroscience Behind EMDR Therapy: A Path to Healing

Understanding the Neuroscience Behind EMDR Therapy: A Path to Healing

Author: Alex Penrod, MS, LPC, LCDC

Eye Movement Desensitization and Reprocessing (EMDR) therapy has gained significant recognition as an effective treatment for trauma and Post-Traumatic Stress Disorder (PTSD). But how does it work? In this article, we'll explore the neuroscience of EMDR, shedding light on its mechanisms and why it has become a cornerstone in trauma therapy. By understanding the science, therapists and clients alike can appreciate the profound impact of EMDR on trauma resolution and greater well-being in general. 

What is EMDR Therapy?

EMDR therapy is a structured evidence-based treatment that involves clients recalling distressing experiences while engaging in bilateral stimulation (BLS), such as side-to-side rapid eye movements, tapping, or auditory tones. BLS is thought to help reprocess and integrate distressing memories, reducing their emotional impact. Originally developed in 1987 by Dr. Francine Shapiro, EMDR's protocols have been researched and refined by the EMDR Institute and the EMDR International Association ever since. EMDR has some of the most robust training and practice guidelines available for a psychotherapy. Some of its biggest proponents include psychiatrist Bessel van der Kolk, a prolific researcher and author in the field of PTSD research.

The Brain and Trauma

To understand how EMDR therapy works, it's essential to first grasp how the brain processes trauma. When a person experiences a traumatic event, the brain's natural processing abilities can become overwhelmed, leading to the event being improperly stored in the memory. This can result in the persistent intrusion of traumatic memories, which can trigger intense physiological and emotional responses, and dysregulation of the nervous system. When a person is triggered by a traumatic memory or external trauma reminder, they are not remembering it as a past episodic memory, it's as if the body and brain believe the event is happening again right now in the present. Traditional therapies that emphasize talking extensively about trauma run the risk of simply reinforcing these reactions resulting in re-traumatization, whereas EMDR aims to desensitize and reprocess the impact of trauma in a targeted manner.

The Role of the Amygdala, Hippocampus, and Prefrontal Cortex

Three critical brain regions are involved in the processing of traumatic memories: the amygdala, hippocampus, and prefrontal cortex.

1. Amygdala: This almond-shaped set of neurons is the brain's emotional center, responsible for detecting fear and preparing for emergency events. During a traumatic event, the amygdala becomes highly active.

2. Hippocampus: This region is involved in forming, organizing, integrating, and storing memories. This helps in contextualizing and distinguishing past from present experiences. The way it organizes and integrates our memories become our identity and life story. Trauma can disrupt the hippocampus’s ability to integrate memories correctly leaving them unprocessed in a disintegrated state.

3. Prefrontal Cortex (PFC): The PFC, part of the frontal lobe, is responsible for executive functions, such as decision-making, rational thought, and emotional regulation. Trauma can impair the prefrontal cortex’s ability to modulate the amygdala's response to fear. Think about how quickly you can slam on the brakes in your car if someone stops short in front of you. That is your amygdala overriding your prefrontal cortex to respond faster than you can think. It’s helpful when you need it, but trauma and PTSD cause this to happen in inappropriate and disruptive ways. The amygdala starts running the show and is not easily convinced that the danger has passed. 

Bilateral Stimulation and Memory Reprocessing

EMDR therapy utilizes bilateral stimulation (BLS), which involves saccadic eye movements, taps, or auditory tones. The exact mechanism of BLS is not fully understood, but several theories provide insights into its effectiveness:

1. Adaptive Information Processing (AIP) Model: The AIP model suggests that trauma disrupts the brain’s information processing system, leaving traumatic experiences stuck in their original form. BLS during EMDR therapy helps to reactivate the brain's natural processing abilities, enabling the integration and resolution of traumatic memories by desensitizing them and connecting them with adaptive information (reprocessing). It’s also thought that by activating both hemispheres of the brain while recalling a traumatic memory this recreates a brain state similar to REM sleep, a process that assists with processing, consolidating, and integrating memories naturally at night. 

2. Dual Attention Stimuli: BLS provides dual attention stimuli, where the client focuses on both the traumatic memory and the external stimuli (e.g., side to side eye movements). This dual focus may reduce the emotional intensity of the memory, allowing for more effective processing. The dual attention aspect can help explain why EMDR allows for successful reprocessing of memories while REM sleep tends to just produce nightmares that further traumatize a person. It seems the AIP network benefits from the aid of BLS to calm the amygdala and make reprocessing tolerable so it to be effective. 

3. Working Memory Explanation: This theory posits that BLS taxes the working memory, which is limited in capacity. When the working memory is occupied with BLS, it has less capacity to fully engage with the traumatic memory, diminishing its vividness and emotional impact. This is useful as another way to throttle and titrate memory exposure so it can be tolerated instead of creating flooding and overwhelm. 

Neurobiology of EMDR Therapy

Research has shown that EMDR therapy can lead to significant neurobiological changes in brain activity. Some of these changes include:

1. Reduction in Amygdala Activation: EMDR therapy has been associated with decreased activation of the amygdala, leading to reduced fear, anxiety, and negative emotions when recalling traumatic memories.

2. Increased Prefrontal Cortex Activity: Enhanced activity in the prefrontal cortex has been observed following EMDR sessions, suggesting improved emotion regulation and cognitive control over traumatic memories. The research that discovered this potential mechanism of action made EMDR the first psychotherapy to have a proven neurobiological effect (Pagani, et al. 2013).

3. Hippocampal Integration: EMDR may facilitate better integration of traumatic memories (memory consolidation) within the hippocampus, aiding in contextualizing the trauma and distinguishing it from present experiences. For an interesting article on some recent discoveries about the hippocampus click here.

Clinical Evidence and Effectiveness of EMDR: Does EMDR Work?

Numerous research studies have demonstrated the effectiveness of EMDR therapy in treating PTSD and other trauma-related disorders. EMDR has shown to be effective with multi-event and complex trauma as well. It’s endorsed as a first line treatment for PTSD by the American Psychiatric Association, The Department of Veterans Affairs, and the World Health Organization, ranking EMDR along with Trauma Focused - Cognitive Behavioral Therapy (TF-CBT).  Clinical trials and systematic reviews have shown that EMDR can lead to significant reductions in PTSD symptoms, with clients often no longer meeting criteria for PTSD. Many studies show PTSD patients experienced significant improvement in 3-12 sessions. A notable difference from talk therapies is that EMDR can often accomplish these benefits in fewer sessions, without needing to describe details of events, and with no homework involved outside of session.

There is emerging yet sparse evidence that EMDR can also be effective for other mental health issues like anxiety disorders, panic disorder, and depression.

One limitation of EMDR research is that it still hasn't confirmed the exact role of eye movements or BLS in general, although the process still delivers desirable results. The American Psychological Association appears to be the only hold-out among authoritative organizations waiting for more evidence, granting EMDR a "conditional recommendation" as a PTSD treatment. Critics argue that EMDR is nothing more than repackaged exposure therapy. If it is, some research shows it to be a more efficient form of it, requiring less exposure time to traumatic memories and achieving faster results. For a comprehensive list of the foundational research on EMDR click here. The Journal of EMDR Practice and Research is also a great open access resource.

Conclusion

Understanding the neuroscience behind EMDR therapy not only enhances its credibility but also provides hope to those suffering from PTSD and complex trauma. By harnessing the brain's natural healing processes, EMDR offers a powerful tool for therapists to help their clients process traumatic memories. As research continues to uncover the intricacies of how EMDR works, its application in clinical practice will only become more refined and effective.

If you’ve been interested in beginning EMDR therapy, and you’re in the state of Texas, consider visiting my home page or booking a free 15-minute consultation.

Alex Penrod, MS, LPC, LCDC

Updated on March 7th, 2025

References

1. Bremner, J. D. (2006). Traumatic stress: Effects on the brain. Dialogues in Clinical Neuroscience, 8(4), 445–461.

2. Knipe, J. (2015). EMDR toolbox: Theory and treatment of complex PTSD and dissociation. New York, NY: Springer Publishing Company.

3. Pagani, M., Di Lorenzo, G., Verardo, A. R., Nicolais, G., Monaco, L., Lauretti, G., Russo, R., Niolu, C., Ammaniti, M., Fernandez, I., & Siracusano, A. (2012). Neurobiological correlates of EMDR monitoring - an EEG study. PloS one, 7(9), e45753.

4. Pagani, M., Högberg, G., Fernandez, I., & Siracusano, A. (2013). Correlates of EMDR therapy in functional and structural neuroimaging: A critical summary of recent findings. Journal of EMDR Practice and Research, 7(1), 29–38.

5. Propper, R., Pierce, J.P., Geisler, M.W., Christman, S.D., & Bellorado, N. (2007). Effect of bilateral eye movements on frontal interhemispheric gamma EEG coherence: Implications for EMDR therapy. Journal of Nervous and Mental Disease, 195, 785-788.

6. Shapiro, F. (2001). Eye Movement Desensitization and Reprocessing (EMDR): Basic principles, protocols, and procedures (2nd ed.). New York, NY: Guilford Press.

7. van der Kolk, B. A. (2014). The body keeps the score: Brain, mind, and body in the healing of trauma. New York, NY: Viking.

8. Vojtova, H., Hasto, J. Neurobiology of Eye Movement Desensitization and Reprocessing. Act Nerv Super 51, 98–102 (2009).