Eye movement intervention facilitates concurrent perception and memory processing.

A widely used psychotherapeutic treatment for post-traumatic stress disorder (PTSD) involves performing bilateral eye movement (EM) during trauma memory retrieval. However, how this treatment-described as eye movement desensitization and reprocessing (EMDR)-alleviates trauma-related symptoms is unclear. While conventional theories suggest that bilateral EM interferes with concurrently retrieved trauma memories by taxing the limited working memory resources, here, we propose that bilateral EM actually facilitates information processing. In two EEG experiments, we replicated the bilateral EM procedure of EMDR, having participants engaging in continuous bilateral EM or receiving bilateral sensory stimulation (BS) as a control while retrieving short- or long-term memory. During EM or BS, we presented bystander images or memory cues to probe neural representations of perceptual and memory information. Multivariate pattern analysis of the EEG signals revealed that bilateral EM enhanced neural representations of simultaneously processed perceptual and memory information. This enhancement was accompanied by heightened visual responses and increased neural excitability in the occipital region. Furthermore, bilateral EM increased information transmission from the occipital to the frontoparietal region, indicating facilitated information transition from low-level perceptual representation to high-level memory representation. These findings argue for theories that emphasize information facilitation rather than disruption in the EMDR treatment.

Does valence contribute to the effects of dual tasking in aversive autobiographical memory? Some unexpected findings.

BACKGROUND AND OBJECTIVES: Lab experiments show that engaging in a working memory task while recalling an aversive memory reduces emotionality and vividness of memories. Studies targeting lab induced negative memory with valenced secondary tasks show promise, but work is needed on autobiographical memories to make it more in line with the original dual tasking research and PTSD treatment in clinical populations. In this study, we address this gap by evaluating differential effectiveness of valenced dual tasks on emotionality and vividness of aversive autobiographical memories. METHODS: University students (N = 178) recalled an aversive autobiographical memory while rating either positive pictures, negative pictures, or while looking at a cross in the exposure only condition. Participants were randomized to one of three aforementioned conditions and rated their memories before and after each intervention on emotionality and vividness. RESULTS: Against expectations, memories became more emotional and vivid regardless of condition. With regard to vividness, this effect was characterized by an interaction effect: memories became more vivid in the exposure only condition than in the combined dual tasking conditions. All effect sizes were small. LIMITATIONS: Working memory load in the dual tasking conditions might have been insufficient. CONCLUSIONS: The current study did not extend findings with regard to (valenced) dual tasking and revealed a possible sensitization effect of script driven autobiographical memory induction. Our study highlights the importance of aspects such as the total amount of exposure and characteristics of memory induction, specifically the addition of a script driven approach to the usual self-initiated memory activation in dual tasking research.

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.

The Effect of modality specific interference on working memory in recalling aversive auditory and visual memories.

Both auditory and visual emotional memories can be made less emotional by loading working memory (WM) during memory recall. Taxing WM during recall can be modality specific (giving an auditory [visuospatial] load during recall of an auditory [visual] memory) or cross modal (an auditory load during visual recall or vice versa). We tested whether modality specific loading taxes WM to a larger extent than cross modal loading. Ninety-six participants undertook a visual and auditory baseline Random Interval Repetition task (i.e. responding as fast as possible to a visual or auditory stimulus by pressing a button). Then, participants recalled a distressing visual and auditory memory, while performing the same visual and auditory Random Interval Repetition task. Increased reaction times (compared to baseline) were indicative of WM loading. Using Bayesian statistics, we compared five models in terms of general and modality specific taxation. There was support for the model describing the effect on WM of dual tasking in general, irrespective of modality specificity, and for the model describing the effect of modality specific loading. Both models combined gained the most support. The results suggest a general effect of dual tasking on taxing WM and a superimposed effect of taxing in matched modality.

Auditory and Visual Memories in PTSD Patients Targeted with Eye Movements and Counting: The Effect of Modality-Specific Loading of Working Memory.

Introduction: Eye movement desensitization and reprocessing (EMDR) therapy is an evidence-based treatment for post-traumatic stress disorder (PTSD). A key element of this therapy is simultaneously recalling an emotionally disturbing memory and performing a dual task that loads working memory. Memories targeted with this therapy are mainly visual, though there is some evidence that auditory memories can also be targeted. Objective: The present study tested whether auditory memories can be targeted with EMDR in PTSD patients. A second objective was to test whether taxing the patient (performing a dual task while recalling a memory) in a modality specific way (auditory demanding for auditory memories and visually demanding for visual memories) was more effective in reducing the emotionality experienced than taxing in cross-modality. Methods: Thirty-six patients diagnosed with PTSD were asked to recall two disturbing memories, one mainly visual, the other one mainly auditory. They rated the emotionality of the memories before being exposed to any condition. Both memories were then recalled under three alternating conditions [visual taxation, auditory taxation, and a control condition (CC), which comprised staring a non-moving dot] - counterbalanced in order - and patients rerated emotionality after each condition. Results: All three conditions were equally effective in reducing the emotionality of the auditory memory. Auditory loading was more effective in reducing the emotionality in the visual intrusion than the CC, but did not differ from the visual load. Conclusion: Auditory and visual aversive memories were less emotional after working memory taxation (WMT). This has some clinical implications for EMDR therapy, where mainly visual intrusions are targeted. In this study, there was no benefit of modality specificity. Further fundamental research should be conducted to specify the best protocol for WMT.

Are addiction-related memories malleable by working memory competition? Transient effects on memory vividness and nicotine craving in a randomized lab experiment.

BACKGROUND AND OBJECTIVES: Experimental research suggests that working memory (WM) taxation reduces craving momentarily. Using a modified Eye Movement Desensitization and Reprocessing (EMDR) procedure, prolonged reductions in craving and relapse rates in alcohol dependence have been demonstrated. Modified EMDR-procedures may also hold promise in smoking cessation attempts. A proof-of-concept study was conducted to narrow the gap between WM-taxation experiments and clinical EMDR studies. To this end the clinical EMDR-procedure was modified for use in a laboratory experiment. METHODS: Daily smokers (n = 47), abstaining overnight, were allocated (by minimization randomization) to one of two groups using a parallel design. In both cases a modified EMDR-procedure was used. In the experimental group (n = 24) eye movements (EM) were induced while control group participants (n = 23) fixed their gaze (not taxing WM). During 6 min trials, craving-inducing memories were recalled. Craving, vividness of target memories, and smoking behavior were assessed at several variable-specific time-points between baseline (one week pre-intervention) and one week follow-up. RESULTS: The experimental group showed significant immediate reductions of craving and vividness of targeted memories. However, these effects were lost during a one-week follow-up period. CONCLUSIONS: A limited dose of WM-taxation, in the form of EM in a modified EMDR-procedure, resulted in transient effects on memory vividness and nicotine craving. EM provide a valuable way of coping with the acute effects of craving during smoking cessation attempts. Other aspects of the EMDR-procedure may provide additional effects. Component and dose-response studies are needed to establish the potential of EMDR-therapy in smoking cessation.

Desensitizing Addiction: Using Eye Movements to Reduce the Intensity of Substance-Related Mental Imagery and Craving.

Eye movement desensitization and reprocessing (EMDR) is an effective treatment for posttraumatic stress disorder. During this treatment, patients recall traumatic memories while making horizontal eye movements (EM). Studies have shown that EM not only desensitize negative memories but also positive memories and imagined events. Substance use behavior and craving are maintained by maladaptive memory associations and visual imagery. Preliminary findings have indicated that these mental images can be desensitized by EMDR techniques. We conducted two proof-of-principle studies to investigate whether EM can reduce the sensory richness of substance-related mental representations and accompanying craving levels. We investigated the effects of EM on (1) vividness of food-related mental imagery and food craving in dieting and non-dieting students and (2) vividness of recent smoking-related memories and cigarette craving in daily smokers. In both experiments, participants recalled the images while making EM or keeping eyes stationary. Image vividness and emotionality, image-specific craving and general craving were measured before and after the intervention. As a behavioral outcome measure, participants in study 1 were offered a snack choice at the end of the experiment. Results of both experiments showed that image vividness and craving increased in the control condition but remained stable or decreased after the EM intervention. EM additionally reduced image emotionality (experiment 2) and affected behavior (experiment 1): participants in the EM condition were more inclined to choose healthy over unhealthy snack options. In conclusion, these data suggest that EM can be used to reduce intensity of substance-related imagery and craving. Although long-term effects are yet to be demonstrated, the current studies suggest that EM might be a useful technique in addiction treatment.

Effects of emotionally valenced working memory taxation on negative memories.

BACKGROUND AND OBJECTIVES: Memories enter a labile state during recollection. Thus, memory changes that occur during recollection can affect future instances of its activation. Having subjects perform a secondary task that taxes working memory while they recall a negative emotional memory often reduces its vividness and emotional intensity during subsequent recollections. However, researchers have not manipulated the emotional valence of the secondary task itself. METHODS: Subjects viewed a video depicting the aftermath of three fatal road traffic accidents, establishing the same negative emotional memory for all subjects. We then tested their memory for the video after randomly assigning them to no secondary task or a delayed match-to-sample secondary task involving photographs of positive, negative, or neutral emotional valence. RESULTS: The positive secondary task reduced memory for details about the video, whereas negative and neutral tasks did not. LIMITATIONS: We did not assess the vividness and emotionality of the subjects' memory of the video. CONCLUSIONS: Having subjects recall a stressful experience while performing a positively valent secondary task can decrement details of the memory and perhaps its emotionality.