EMDR and the Brain: Why This Therapy Works for Trauma and PTSD

To understand why EMDR is effective, it is important to recognize what is happening in the brain and the body during and after traumatic events.

Key Brain Structures Involved in Trauma

Amygdala (Fear & Emotional Processing):

This almond-shaped structure helps a person identify and respond to perceived threats, integrating information received from your senses (what you see, hear, feel, smell and taste). When the amygdala detects a threat it triggers the body’s fight-or-flight response, making the amygdala vital for survival. So, what does that look like in action? Say, for example, you are walking down the street and a car backfires behind you. You immediately startle, turn around, and gasp. You feel your muscles tense, your heart rate increases, and you begin to take more frequent and shallower breaths. This is your amygdala and central nervous system at work. It can bypass other processes and move your body in a way that it believes is the safest. Another primary function of the amygdala is to learn from those scary experiences so the brain and body can respond appropriately in the future.

When someone experiences trauma, the amygdala may become overactive, making it more sensitive to perceived threats. This heightened sensitivity may lead to hypervigilance, exaggerated startle responses, and difficulty distinguishing between real and perceived threats. The overactivation of the amygdala can increase anxiety, emotional outbursts and make it more difficult to process emotions effectively. These responses can impair rational thinking, making individuals more prone to impulsive or avoidant behaviors.

Hippocampus (Memory Storage & Context):

This part of the brain is responsible for forming and storing memories, including contextualizing those memories in time and space. It also helps differentiate between past and present experiences. After trauma, it may be difficult for the hippocampus to recognize traumatic memories coherently. As a result, memories may become fragmented or distorted. In addition, the disruption in hippocampal functioning can cause people to feel like past events are still happening in the present (e.g. flashbacks).

Let’s use our previous example of the car backfiring to help show what this looks like. When the car backfires, you immediately startle, turn around, and feel your heart race. Your amygdala has triggered the fight-or-flight response, preparing your body for danger. Under normal circumstances, your hippocampus helps process this experience, encoding details like the location, time of day, and context, allowing your brain to recognize that it was just a loud noise and not an actual threat. Later, if you hear a similar sound, your hippocampus can help you recall that the previous event was not dangerous, allowing you to respond more calmly. However, when someone experiences trauma, the hippocampus can become impaired, making it harder to properly store and contextualize memories. If a person with trauma hears a car backfire, their hippocampus might struggle to differentiate between the present moment and past traumatic experiences involving loud noises. This means their brain may react as if they are in real danger, even if they are safe. Instead of recognizing it as just another loud noise, they may feel as though they are reliving a past traumatic event, leading to an intense fear response, flashbacks, or panic.

Because of this dysfunction, people who have experienced trauma may find themselves constantly on edge, unable to trust their surroundings, and react disproportionately to everyday stimuli. The hippocampus, when affected by trauma, struggles to create a clear timeline of events, causing past threats to feel as immediate and real as present ones.

Prefrontal Cortex (Rational Thinking & Regulation):

The prefrontal cortex is responsible for logical reasoning and emotional regulation. Trauma can decrease its activity, making it harder for individuals to regulate emotions or rationalize that they are no longer in danger.

One last time, let’s use the example of the car backfiring. When a car suddenly backfires, you startle, your muscles tense, and your heart rate spikes. Your amygdala has triggered the fight-or-flight response. However, within moments, your prefrontal cortex steps in to assess the situation logically. It helps you recognize that the noise was just a car backfiring, not a real threat. You take a deep breath, calm yourself down, and continue walking, realizing there’s no immediate danger.

Now, in the case of trauma, the prefrontal cortex’s ability to regulate emotional responses is weakened. If someone with trauma hears a car backfire, their amygdala might instantly react as if they are in danger, but their prefrontal cortex struggles to step in and provide reassurance. Instead of logically assessing the situation, they might stay in a heightened state of fear, experiencing panic, dissociation, or an overwhelming sense of danger. Because trauma disrupts the communication between the prefrontal cortex and the amygdala, the individual may struggle with emotional regulation, making it difficult to calm down even when no real threat is present. This can lead to persistent anxiety, difficulty making rational decisions under stress, and impulsive or avoidant behaviors.

Connecting Neuroscience to EMDR’s Therapeutic Impact

EMDR helps the brain reprocess traumatic memories and store them in a more adaptive way by engaging bilateral stimulation (BLS). This process mimics the brain’s natural healing mechanism and is believed to create new neural connections that change how traumatic memories are stored.

Neurobiological Mechanisms of EMDR:

Dual Attention Processing: The therapist guides the client to focus on distressing memories while simultaneously engaging in bilateral stimulation (eye movements, tapping, or auditory tones). This prevents emotional overwhelm and keeps the client anchored in the present.

Desensitization of Emotional Responses: Research suggests that EMDR reduces amygdala hyperactivity, decreasing emotional intensity when recalling traumatic events.

Increased Integration Between Brain Hemispheres: Bilateral stimulation is thought to activate both hemispheres of the brain, facilitating better communication between the emotional (right hemisphere) and logical (left hemisphere) processing centers. This helps the individual reframe negative beliefs and process trauma in a less distressing way.

Enhanced Neuroplasticity & Memory Reconsolidation: EMDR leverages the brain’s ability to form new neural pathways (neuroplasticity). Studies suggest that EMDR promotes memory reconsolidation, allowing the brain to reprocess traumatic memories and store them more like ordinary memories, rather than ongoing threats.

Reduction of Maladaptive Neural Networks: Trauma is believed to be stored in dysfunctional neural networks, which trigger negative emotions, body sensations, and distorted self-beliefs. EMDR helps weaken these old neural pathways and strengthen new, healthier associations.

If trauma has shaped how your brain processes the world, EMDR offers a chance to gently reshape those patterns. By targeting the very systems that keep you stuck in survival mode, EMDR helps your brain do what it was always meant to do: heal. If you’re curious about how this process might help you feel safer in your body, more present in your life, and more connected to yourself and others, we would be honored to support you on that journey.

Our EMDR therapists are Kerry, Steve, and Gina. 

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