Electroencephalography Coherence, Memory Vividness, and Emotional Valence Effects of Bilateral Eye Movements During Unpleasant Memory Recall and Subsequent Free Association: Implications for Eye Movement Desensitization and Reprocessing

Saccade-induced retrieval enhancement and the recovery of perceptual item-specific information

Saccade-induced retrieval enhancement (SIRE) effects refer to the finding that memory can be enhanced when a short period of saccadic eye movements takes place prior to retrieval. Previous published work testifies to this eye movement advantage, but no work has yet examined if SIRE effects can be found when retrieval demands are high as a result of testing non-studied memoranda that are identical in name/conceptual codes, similar in perceptual features, but differ in terms of perceptual-item-specific information. The results indicate SIRE effects can be found under such conditions and are independent of encoding orientation (intentional vs. incidental). More particularly, SIRE effects manifested themselves in terms of the retrieval of item-specific detail and recollection (vs. familiarity). In terms of the latter, recollection but not familiarity was enhanced by eye movements. These findings are considered in the context of extant theories of SIRE and related research.

Should we pay attention to eye movements? The impact of bilateral eye movements on behavioral and neural responses during the Attention Network Test

Bilateral eye movements (EMs) have been associated with enhancements in episodic memory and creativity. We explored the influence of EMs on behavior and event related potential (ERP) responses during the Attention Network Test (ANT). Participants completed ANT trials after bilateral EMs or a center-fixation control manipulation. We examined condition (EM, control) and handedness (consistent, inconsistent) differences for overall task performance, as well as alerting, orienting, and executive attention networks. Behaviorally, there was a trend for inconsistent-handed participants to display faster RTs across cue types, and greater accuracy for no cue, double, and center cue trials when compared to consistent handers, yet consistent handers garnered greater improvements in behavior following altering and orienting cues than inconsistent handers. Although there were no behavioral differences between EM and control conditions, target-locked N100 and P200 ERPs were weaker in the EM than control condition for all cue types, except spatial cues for which there were no differences between groups. Because stronger N100 and P200 responses have been linked to increased selective attention, we speculate that ERP differences between EM and control conditions, in the absence of behavioral differences, may indicate that participants exposed to EMs required less selective attention to successfully complete the task.

Neurobiological features and response to eye movement desensitization and reprocessing treatment of posttraumatic stress disorder in patients with breast cancer

Background: Breast cancer (BC) is one of the most common invasive types of cancer among women, with important consequences on both physical and psychological functioning. Patients with BC have a great risk of developing posttraumatic stress disorder (PTSD), but few studies have evaluated the efficacy of psychological interventions to treat it. Furthermore, no neuroimaging studies have evaluated the neurobiological effects of psychotherapeutic treatment for BC-related PTSD. Objective: The study aimed to evaluate the efficacy of Eye Movement Desensitization and Reprocessing therapy (EMDR) as compared to Treatment as Usual (TAU) in BC patients with PTSD, identifying by electroencephalography (EEG) the neurophysiological changes underlying treatments effect and their correlation with clinical symptoms. Method: Thirty patients with BC and PTSD diagnosis were included, receiving either EMDR (n = 15) or TAU (n = 15). Patients were assessed before and after treatments with clinical questionnaires and EEG. The proportion of patients who no longer meet criteria for PTSD after the intervention and changes in clinical scores, both between and within groups, were evaluated. Two-sample permutation t-tests among EEG channels were performed to investigate differences in power spectral density between groups. Pearson correlation analysis was carried out between power bands and clinical scores. Results: At post-treatment, all patients treated with EMDR no longer met criteria for PTSD, while all patients treated with TAU maintained the diagnosis. A significant decrease in depressive symptoms was found only in the EMDR group, while anxiety remained stable in all patients. EEG results corroborated these findings, showing significant differences in delta and theta bands in left angular and right fusiform gyri only in the EMDR group. Conclusions: It is essential to detect PTSD symptoms in patients with BC, in order to offer proper interventions. The efficacy of EMDR therapy in reducing cancer-related PTSD is supported by both clinical and neurobiological findings.

Reducing the Emotionality of Auditory Hallucination Memories in Patients Suffering From Auditory Hallucinations

Eye movement desensitization and reprocessing (EMDR) therapy targets emotionally disturbing visual memories of traumatic life events, and may be deployed as an efficacious treatment for posttraumatic stress disorder. A key element of EMDR therapy is recalling an emotionally disturbing visual memory while simultaneously performing a dual task. Previous studies have shown that auditory emotional memories may also become less emotional as a consequence of dual tasking. This is potentially beneficial for psychotic patients suffering from disturbing emotional auditory memories of auditory hallucinations. The present study examined whether and to what extent emotionality of auditory hallucination memories could be reduced by dual tasking. The study also assessed whether a modality matching dual task (recall + auditory taxation) could be more effective than a cross modal dual task (recall + visual taxation). Thirty-six patients suffering from auditory hallucinations were asked to recall an emotionally disturbing auditory memory related to an auditory hallucination, to rate emotionality of the memory, and to recall it under three conditions: two active conditions, i.e., visual taxation (making eye-movements) or auditory taxation (counting aloud), and one control condition (staring at a non-moving dot) counterbalanced in order. Patients re-rated emotionality of the memory after each condition. Results show the memory emotionality of auditory hallucinations was reduced and the active conditions showed stronger effects than the control condition. No modality-specific effect was found: the active conditions had an equal effect.

How Does Eye Movement Desensitization and Reprocessing Therapy Work? A Systematic Review on Suggested Mechanisms of Action

Background: Eye movement desensitization and reprocessing [EMDR] is an innovative, evidence-based and effective psychotherapy for post-traumatic stress disorder [PTSD]. As with other psychotherapies, the effectiveness of EMDR contrasts with a limited knowledge of its underlying mechanism of action. In its relatively short life as a therapeutic option, EMDR has not been without controversy, in particular regarding the role of the bilateral stimulation as an active component of the therapy. The high prevalence of EMDR in clinical practice and the dramatic increase in EMDR research in recent years, with more than 26 randomized controlled trials published to date, highlight the need for a better understanding of its mechanism of action.

Methods: We conducted a thorough systematic search of studies published until January 2018, using PubMed, ScienceDirect, Web of Knowledge and Scopus databases that examined the mechanism of action of EMDR or provided conclusions within the framework of current theoretical models of EMDR functioning.

Results: Eighty-seven studies were selected for review and classified into three overarching models; (i) psychological models (ii) psychophysiological models and (iii) neurobiological models. The evidence available from each study was analyzed and discussed. Results demonstrated a reasonable empirical support for the working memory hypothesis and for the physiological changes associated with successful EMDR therapy. Recently, more sophisticated structural and functional neuroimaging studies using high resolution structural and temporal techniques are starting to provide preliminary evidence into the neuronal correlates before, during and after EMDR therapy.

Discussion: Despite the increasing number of studies that published in recent years, the research into the mechanisms underlying EMDR therapy is still in its infancy. Studies in well-defined clinical and non-clinical populations, larger sample sizes and tighter methodological control are further needed in order to establish firm conclusions.

Changes in brain connectivity following exposure to bilateral eye movements

The present research assessed how engaging in bilateral eye movements influences brain activity. Participants had their resting-state brain activity recorded with electroencephalography (EEG) before and after they performed 30 s of bilateral eye movements or a center-control manipulation. We assessed differences in change scores for absolute power and coherence between the eye-movement and center-control conditions. A main effect for handedness was present for EEG power in the theta and beta frequency bands, with inconsistent-handed participants displaying a greater increase than consistent-handed participants in both frequency bands. For theta, the increase in power for inconsistent handers was specific to participants in the bilateral eye-movement condition, whose increase in theta power exceeded the increase in theta power for consistent-handed participants regardless of condition. In contrast, for coherence, a main effect for condition was present for the delta frequency band, with participants in the control condition exhibiting a significant drop in posterior delta coherence pre to post. We suggest that the maintenance of posterior delta coherence over time may be an important factor in sustaining attention. Further, the malleability of EEG power for inconsistent-handed participants reveals the importance of individual-differences variables in the potential for behavioral manipulations to change brain activity.

Effects of Saccade Induced Retrieval Enhancement on conceptual and perceptual tests of explicit & implicit memory

The effects of saccadic horizontal (bilateral) eye movements upon tests of both conceptual and perceptual forms of explicit and implicit memory were investigated. Participants studied a list of words and were then assigned to one of four test conditions: conceptual explicit, conceptual implicit, perceptual explicit, or perceptual implicit. Conceptual tests comprised category labels with either explicit instructions to recall corresponding examples from the study phase (category-cued recall), or implicit instructions to generate any corresponding examples that spontaneously came to mind (category-exemplar generation). Perceptual tests comprised of word-fragments with either explicit instructions to complete these with study items (word-fragment-cued recall), or implicit instructions to complete each fragment with the first word that simply 'popped to mind' (word-fragment completion). Just prior to retrieval, participants were required to engage in 30 s of bilateral vs. no eye movements. Results revealed that saccadic horizontal eye movements enhanced performance in only the conceptual explicit condition, indicating that Saccade-Induced Retrieval Enhancement is a joint function of conceptual and explicit retrieval mechanisms. Findings are discussed from both a cognitive and neuropsychological perspective, in terms of their potential functional and neural underpinnings.

Fifteen to Twenty Seconds of Eye Movements Have No Effect on Believability of Positive Personal Verbal Statements: Results From a Working Memory Study

According to working memory theory, a task that taxes working memory during simultaneous focus on a memory will tend to reduce memory vividness and emotional intensity. Results have been found for both negative and positive memories. Some studies have shown the necessity of modality-specific tasks, with visual tasks producing greater deterioration of a visual memory, and auditory tasks reducing the quality of an auditory or verbal memory; other studies have reported cross-modality effects. Research has confirmed that eye movements similar to those in eye movement desensitization and reprocessing (EMDR) therapy produce these effects on visual imagery. However, the effects of eye movements on positive verbal imagery remain unclear. This study tested the effects of eye movements on positive verbal statements. In two experiments, undergraduates performed 15–20 seconds of eye movements or 15–20 seconds of keeping eyes stationary while focusing on a statement of a positive relevant personality trait (e.g., “I’m persistent”). Results showed that 15–20 seconds of eye movements did not enhance or diminish participant’s belief in possessing the trait. Discussion focuses on methodological factors and calls for future research on the effect of eye movements on verbal material.