What is memory consolidation?
Memory consolidation involves taking the component parts of a memory and combining them into one unified whole. In the first few months after an event occurs, it is still fragmented into its component parts. After that the different parts of the memory come together into more of a single whole entity.
What does the term "overconsolidation" mean?
When a memory is overconsolidated, it is continually re-activated by reminders and does not fade with time. Traumatic memories are often overconsolidated into flashbacks. Every time a flashback occurs, it reinforces the overconsolidation of the memory, making it more and more resistant to change.
What is meant by reconsolidation?
It was previously believed that the consolidation process occurred just once, but research findings indicate that memory retrieval activates reconsolidation, a process that either reinforces or alters memory.* Reconsolidation of the memory means that the whole memory network is altered because of new information. Younger and weaker memories are more easily reconsolidated than older and stronger memories.*
How does EMDR facilitate reconsolidation?
EMDR reprocessing involves brief retrieval of a traumatic memory with delineation of all of its component parts (sensory, cognitive, affective and somatic aspects). Bilateral stimulation is added to facilitate reprocessing that updates the memory with new adaptive information. This reconsolidation of the memory puts it in a different perspective, so that reminders no longer trigger flashbacks or fight/flight/freeze reactions.
Trauma-based memory networks are like files in a filing cabinet that are isolated from the other files. With EMDR, the isolated files are able to access files with information needed to put a traumatic event in time perspective, create a coherent narrative and find meaning in the experience.
How is this different than what happens with prolonged exposure (PE)?
With PE, extinction is achieved by repeatedly re-exposing subjects to the feared situation without the feared result. In this way, over time, the feared situation no longer elicits the fear-based response. In my understanding, extinction does not involve the elimination of the original association, but involves new learning that competes with the original conditioning to weaken the conditioned response. Therefore, extinction of emotional arousal and urges does not eliminate the underlying traumatic associations, just the symptoms.
With EMDR reconsolidation, the original association appears to be unlinked and the new learning is linked to the original events and resulting beliefs, feelings and body-based symptoms.
In summary, the EMDR and Prolonged Exposure methods of treating trauma involve two different approaches to therapeutic memory retrieval and initiate two different processes: reconsolidation and extinction. According to recent studies using crab and medaka fish, the duration of the re-exposure may be an important factor regarding the type of memory processing that is elicited: brief retrieval led to reconsolidation, while more prolonged retrieval resulted in memory extinction.*
What does the EMDR experience look like?
For a taste of what EMDR therapy is like, here is a link to a CBS News report on Healing Post Traumatic Stress about a gulf war soldier who received EMDR from San Diego trauma therapist Sara Gilman, past president of the EMDR International Association (EMDRIA).http://www.youtube.com/watch?v=LM_nw5N3n-I
Source:Suzuki, A., et al. (2004). Memory Reconsolidation and Extinction Have Distinct Temporal and Biochemical Signatures. The Journal of Neuroscience, 24(20):4787-4795. http://www.jneurosci.org/content/24/20/4787.full