Neuropsychological Findings on BLS
EMDR is considered a complex protocol due to itsvarious components: cognitive, behavioral, physical, and emotional. Several therapeutic aspects emerge in this form of psychotherapy, such as exposure and desensitisation, focus on physical sensations self-mastery reinforcement, reconnection of disseminated parts of the painful memory and the integration of these parts into memory, cognitive reprocessing,and bilateral stimulation.
During bilateral stimulation, therapists typically move their fingers horizontally (left-right) or vertically in order to elicit a response in the form of eye movements. As an alternative, they can also use an ellipsoid or oblique trajectory, or they can operate a technical device to replace finger movement, such as a light bar. Bilateral stimulation can also be auditory (i.e., an alternating sound in left and right ears) or tactile (i.e., a stimulation of anypart of the body from left to right) as well, not just visuomotor. Online EMDR Clinic in Melbourne uses software to produce both visual and auditory BLS.
A 2013 study conducted in the US examined the effects of eye movements on episodic memory retrieval by using bilateral eye movementsin order to temporarily increase the amount of interaction between the left and right hemispheres. Undergraduate students participated in two experiments that involved episodic memory tests. Beforetaking the tests, the participants engaged in eye movements. The movements were either smooth or saccadic pursuit, and either vertical or horizontal. Only bilateral horizontal saccadic eye movements facilitated retrieval of episodic memories. The authors suggestedthat bilateral saccadic eye movements enhance interhemispheric interaction, which subsequently facilitates episodic memory retrieval. The authors also suggested that the role of eye movements in EMDR may be that of helping clients retrieve episodic memories of their traumatic experiences. The study highlighted that it was just horizontal saccadic, and not smooth pursuit eye movements that generatedmajor improvements in retrieving episodic memories.More research is required in order to differentiate between the effects of distinct types of eye movements in terms of episodic memory retrieval.
Another study conducted in 2009 also found that the performance of the participants on episodic memory retrieval test improved when preceded by horizontal eye movements compared to vertical eye movements or an eyes-stationary condition. In addition, eye movements improved performance exclusively on tasks which required large amounts of left and right hemisphere processing. These results reinforce the notion that bilateral horizontal eye movements increase interhemispheric interaction. Thus, the eye movement component of EMDR therapy could facilitate both the recollection and the integration of episodic memories by using the interhemispheric interaction mechanism.Even so, results vary in terms of what is most effective regarding bilateral stimulation. For instance, a 2012 study conducted in the Netherlands showed that, while horizontal eye movements and alternating left-right tactile stimulation had beneficial effects on memory retrieval, alternating left–right auditory stimuli did not lead to the same outcome.
Also related to the neuropsychological effects of this form of psychotherapy and its components, a 2015 quantitative single-case studyon the neurocognitive impact of PTSD investigated whether EMDRcouldmodify the neuropsychological and physiological responses of a female client aged 18. The participant was diagnosed with comorbid PTSD and major depressive disorder. Eleven 90-minute sessions of EMDR therapy were provided on a weekly basis. The study found a heart rate decrease between baselines at the start and end of treatment. Neuropsychological evaluations of memory, attention, and brain executive functions showed pretreatment impairments related to information processing speed, attentional processes, and working memory and posttreatment improvement of the aforementioned cognitive functions, with major differences on the Paced Auditory Serial Addition Test. The authors discovered a significant posttreatment decrease in mean scores on the Beck Depression Inventory-II, as well as on the Dissociative Experiences Scale. In addition, the participant showed no symptoms of PTSD after the treatment,based on Posttraumatic Stress Global Scale. At the 1-year follow-up, the participant reported continuity of treatment effects. While the results were positive, the case study had its limitations. Firstly, generalisation is impossible due to the fact that there was only one participant. Secondly, the participant did not have any appointment with a therapist, so there were no third parties to confirm the positive changes. The study was successful, but further research is required in order to better understand whether EMDR therapy leads to the neurocognitive changes and how.
There are also studies which have generated less favorable conclusions regarding bilateral stimulation and EMDR. For instance, research conducted in 2011showed no increase in interhemisphericelectroencephalogram(EEG) coherence, indicatingthat more research is needed to discover firstly whether eye movements increase interhemispheric interaction and, if so, precisely how they do so. Similarly, a 2007 study showeddecreased gamma frequency coherence linked to engaging in 30 seconds of bilateral eye movementswhile keeping the eyes open. These findings were surprising, but they correspond with a 2005 functional magnetic resonance imaging study. The latterfound decreased functional interaction between the left and right hemispheres in the anterior prefrontal cortex during episodic memory retrieval.The reason why this should be the case exclusively when the eyes are kept open after eye movements are yet unclear; this issue should certainly be addressed in future studies.
EMDR is a complex form of psychotherapy which involves a number of underlying processes that work simultaneously. Multiple mechanisms may produce positive results in EMDR; because of this, an integrative model could be necessary in order to discover its numerous effects. At the present, EMDR online clinic in Melbourne uses to horizontal eye movements through online software and auditory stimulus to produce BLS.
An appropriate example of this is the 2016 integrative model for the neural mechanism of EMDR, which was proposed by Coubard. The model integrates neurophysiological findings on eye movement, theories of EMDR, as well as functional brain imaging of PTSD to analyse attentional and/or emotional disorders (for instance, anxiety disorders).The neurobiological underpinning of limbic regulation, temporal binding, reciprocal anterior cingulate cortex suppression, and frontal lobe activation are sufficiently interconnected to prevent mutual exclusion and should be evaluated in well-designed studies in which reliable, multidimensional neurobiological indexes are used. Future results will certainly shed increasing light on the way in which different mechanisms interact in the treatment outcomes of EMDR therapy.