Neurobiology and Stochastic Resonance: Going Deeper

Abstract

This section is to inform therapists who have clients who want more detail on the proposed science of the eye movement desensitization and reprocessing (EMDR) method. It will not be necessary to go into such detail with all clients, but better to have this knowledge and not need it, than to need it and not have it; so here is a summary of the latest research and publications. THALAMIC ACTIVITY AND PTSDIn patients with posttraumatic stress disorder (PTSD), where the naturally occurring noise from descending cortico-thalamic feedback is presumed to be unavailable due to a decrease in thalamic activity (Bergmann, 2008;Sartory et al., 2013; Yan et al., 2013) seen in PTSD, the dual attention stimulation/bilateral stimulation (DAS/BLS) of EMDR therapy could be generating a random (stochastic) signal at the thalamic level. Stochastic resonance (SR) in this setting would presumably facilitate the sensing of a signal that would otherwise be subthreshold. In other words, a further signal is transmitted that would otherwise not be. The principle of boosting an undetectable signal by having it resonate with added white noise is an area of intense research (Moss, Ward, & Sannita, 2004). So although noise may seem a worthless thing in one context, it can be the essential phenomenon for generating a meaningful signal in another. This observation has led one researcher in this area to state, "One man's noise is another man's signal" (Kosko, 2006). REVIEW OF PROPOSED MECHANISMS OF ACTION OF DAS/BLS ELEMENT OF EMDR THERAPYDAS/BLS is the element of the EMDR method that raises the most questions, controversy, and derision. One of the earliest and most influential authors who examined the effects of eye movements and their role within EMDR therapy states, "A major bar to the further acceptance of EMDR as a treatment and as an inviting