THE NEUROBIOLOGY OF HOW EMDR WORKS

We have assumed for a long time that there are three fear circuits in the brain: fight, flight or freeze. Based on very recent research it turns out that’s not the case. There is only one fear circuit that includes both freeze or flight. Fight is not part of this process. 

The freeze/flight circuit is deep in the brain in an area called the amygdala. The amygdala is connected to other areas of the brain and it can therefore affect other areas of the brain. One of these affected areas can be the prefrontal cortex (PFC). The PFC is a major decision making area of the brain. If fear is too high in the amygdala it can reduce the PFC’s ability to solve the fear problem so freeze or run become the only alternatives. We now know that fight is not part of that fear circuit, it is it’s own separate circuit and it is activated by moving toward the fear versus running/flight or hiding/fright. 

When we move towards the fear (committed actions like walking and or running) our body’s motion causes a crossing of the midline.(Crossing the midline is when we move our arm or leg across the middle of our body to perform a task). To try this out, pick a small spot on a wall 15-20 feet in front of you. Keeping your eyes fixed on the spot, slowly walk toward it and notice how the spot moves slightly from side to side as a result of your binocular vision. Another way to do this is by standing or sitting still and focusing on an object just a few feet in front of you and close one eye while keeping the other eye open, then reverse the process; closing the open eye and opening the closed eye. Notice the change in perspective (a bilateral shift). 

 The crossing of the midline reduces the amygdala activity. When the midline is crossed dopamine is released. Dopamine is the neurochemical the PFC needs to solve problems. Dopamine down-regulates the fear response and up-regulates the planning, and problem solving processes of the PFC.

Dr. Francine Shapiro discovered the effect of reducing fear before we understood the underlying neurological process when she was rapidly visually bilaterally tracking (crossing the midline) after receiving some very fearful health news. She noted that this rapid visual tracking reduced her anxiety and she began a series of experiments to replicate her findings with others. The result is what we now know as EMDR therapy. To summarize the bilateral visual tracking of EMDR simulates moving toward the fear, in other words, the fight state. When this occurs fear is reduced by a down-regulation of the amygdala and an up-regulation of the PFC.

The next piece of the EMDR puzzle involves understanding sleep and memory. There are basically two types of sleep: slow wave sleep (Delta waves) and fast wave sleep (Alpha and Theta waves). Fast wave sleep is Rapid Eye Movement (REM) sleep. Here we go again with bilateral eye movements. REM sleep involves the processing of emotional memories while slow wave sleep processes non-emotional information (episodic memory). Episodic memory (EM) is the memory system of everyday events. 

Following encoding during sleep, memory then appears to require “consolidation,” which refers to the process of memory stabilization over time, making it more resistant to interference or disruption. Traumatic memories are believed to be unconsolidated or destabilized, in other words not adequately processed in the brain. For these REM memories consolidation seems to fail. 

The last important discovery from neuroscience has been the discovery of memory reconsolidation. In contrast to the idea that memory once formed is resistant to change, reconsolidation theory holds that after the retrieval or reactivation of a memory, it becomes labile and modifiable. Dr. Shapiro intuited this neurological process as well when she had her subjects rapidly visually bilaterally tracking (crossing the midline) while recalling a traumatic memory from their past. She found that this rapid visual tracking reduced the strength of the traumatic (fast wave/REM) unconsolidated memory that may have been troubling them for years or decades. 

These breakthroughs offer our best understanding of what Dr. Shapiro called the Alternative Information Processing (AIP) model of PTSD.