Bilateral eye movements disrupt the involuntary perceptual representation of trauma-related memories.

Bilateral eye movement (EM) is a critical component in eye movement desensitization and reprocessing (EMDR), an effective treatment for post-traumatic stress disorder. However, the role of bilateral EM in alleviating trauma-related symptoms is unclear. Here we hypothesize that bilateral EM selectively disrupts the perceptual representation of traumatic memories. We used the trauma film paradigm as an analog for trauma experience. Nonclinical participants viewed trauma films followed by a bilateral EM intervention or a static Fixation period as a control. Perceptual and semantic memories for the film were assessed with different measures. Results showed a significant decrease in perceptual memory recognition shortly after the EM intervention and subsequently in the frequency and vividness of film-related memory intrusions across one week, relative to the Fixation condition. The EM intervention did not affect the explicit recognition of semantic memories, suggesting a dissociation between perceptual and semantic memory disruption. Furthermore, the EM intervention effectively reduced psychophysiological affective responses, including the skin conductance response and pupil size, to film scenes and subjective affective ratings of film-related intrusions. Together, bilateral EMs effectively reduce the perceptual representation and affective response of trauma-related memories. Further theoretical developments are needed to elucidate the mechanism of bilateral EMs in trauma treatment.

Computational discrimination between natural images based on gaze during mental imagery.

When retrieving image from memory, humans usually move their eyes spontaneously as if the image were in front of them. Such eye movements correlate strongly with the spatial layout of the recalled image content and function as memory cues facilitating the retrieval procedure. However, how close the correlation is between imagery eye movements and the eye movements while looking at the original image is unclear so far. In this work we first quantify the similarity of eye movements between recalling an image and encoding the same image, followed by the investigation on whether comparing such pairs of eye movements can be used for computational image retrieval. Our results show that computational image retrieval based on eye movements during spontaneous imagery is feasible. Furthermore, we show that such a retrieval approach can be generalized to unseen images.

Driver eye movements in relation to unfamiliar traffic signs: An eye tracking study.

Traffic signs are an integral part of the traffic control plan and they provide road users with necessary information on the upcoming situation. This paper aims to examine the level of understanding of traffic sign imagery used in different countries and to track participants' eye movement when they encounter unfamiliar signs. Tobii eye tracking glasses were used to track gaze differences between familiar and unfamiliar traffic signs. Our findings show that sign characteristics (such as the amount of information on the sign) and the observer's knowledge of the sign meaning have a significant impact on eye behaviour. Signs containing more information (loaded with more content) and unfamiliar to the participant systematically produced the longest overall and average fixations and gazing duration. Given that longer gaze time for unfamiliar traffic signs presents a potential traffic hazard, we evaluated the need for standardization of traffic signs.

Children's and parents' looking preferences to gender-typed objects: Evidence from eye tracking.

Differences between children's and parents' implicit and explicit gender stereotypes were investigated in two experiments. For the first time, the visual world paradigm compared parents' and 7-8-year-old children's looking preferences toward masculine- and feminine-typed objects stereotypically associated with a story character's gender. In Experiment 1 participants listened to sentences that included a verb that inferred intentional action with an object (e.g., "Lilly/Alexander will play with the toy"), and in Experiment 2 the verb was replaced with a neutral verb (e.g., "Lilly/Alexander will trip over the toy"). A questionnaire assessed participants' explicit gender stereotype endorsement (and knowledge [Experiment 2]) of children's toys. Results revealed that parents and children displayed similar implicit stereotypes, but different explicit stereotypes, to one another. In Experiment 1, both children and parents displayed looking preferences toward the masculine-typed object when the story character was male and looking preferences toward the feminine-typed object when the character was female. No gender effects were found with a neutral verb in Experiment 2, reinforcing the impact of gender stereotypes on implicit processing and showing that the effects are not simply driven by gender stereotypic name-object associations. In the explicit measure, parents did not endorse the gender stereotypes related to toys but rather appeared to be egalitarian, whereas children's responses were gender stereotypic.

Conceptual relation preference: A matter of strategy or one of salience?

In order to determine whether preference in object matching tasks measures participants' strategy or tells us something about the salience of relations between corresponding concepts, we conducted three experiments. In Experiment 1 and Experiment 2, we approached this question by measuring the ease with which adult participants process different relations when they are under strategic instruction. When asked to group objects based on thematic or taxonomic relatedness, participants were slower (Experiment 2) and tended to make more errors (Experiment 1-2) when they had to find a taxonomically related pair than when they searched for a thematically related one. In Experiment 3, participants performed a standard matching task and their eye-movements were monitored throughout. In addition to the strong thematic preference in participants' choices, we measured longer fixations to thematically related objects than taxonomic competitors. Even though thematic and taxonomic information appear to compete for selection in early phases of observation, thematic conceptual relations appear to be more salient and preferred, independently of instruction.

Increases of correct memories and spontaneous false memories due to eye movements when memories are retrieved after a time delay.

Eye Movement Desensitization and Reprocessing (EMDR) is an effective treatment for post-traumatic stress disorder. However, literature on possible adverse memory effects of EMDR is scarce. Using the Deese/Roediger-McDermott (DRM) false memory paradigm, we examined the susceptibility to spontaneous false memories after performing eye movements, as used in EMDR. In Experiment 1, 72 undergraduates received word lists containing negative and neutral associated words and immediately after this they were given a free recall and recognition test. In Experiment 2, 68 undergraduates underwent the free recall and recognition test 48 h later. During the free recall phase in both experiments, participants either performed eye movements or not (control condition). In Experiment 1, the two conditions did not differ statistically with regard to correct and false recall/recognition. In Experiment 2, correct memory rates were higher in the eye movement than in the control condition and this was accompanied by an increase in spontaneous false memories on both free recall and recognition. Although our experimental approach is far removed from clinical practice, our findings suggest that eye movements as used in EMDR might amplify both correct and false memory rates.

Ophthalmic features and management outcomes of 30 children having Goldenhar syndrome.

PURPOSE: To study the ophthalmic clinical profile and the management outcomes of children having Goldenhar syndrome (GS). METHODS: Retrospective review of included children fulfilling the diagnostic criteria of GS was performed. The demography, ophthalmic features, systemic anomalies, and treatment outcomes were recorded manually from patient files. An ENT, pediatrics, cardiology, and orthopedics consultation was sought for all GS patients before taking up for any ophthalmic surgical procedure. The anatomical (ocular surface and eyelid) and functional {vision and extraocular movements (EOM)} factors were exclusively studied. We ensured a minimum postoperative follow-up of 12 months, and our data were compared with the major studies featuring 'ophthalmic features' of GS. RESULTS: Totally 30 children (females = 18, 60%) were included with a median presenting age of 48 months. Twenty-seven (90%) had unilateral ophthalmic involvement with major features being upper eyelid coloboma (n = 25, 75.76%), lipodermoid (n = 18, 54.55%), and limbal dermoid (n = 10, 30.3%). Diminution of visual acuity was recorded in 22 (73.3%), while five (16.7%) had limitation of EOM. Systemically, the prominent features included hemifacial hypotrophy (100%), auricular anomalies (80%), cardiac anomalies (10%), and scoliosis (6.67%). The eyelid colobomas were repaired with the direct closure ± cantholysis technique or using a Tenzel's flap. All children had satisfactory anatomical and functional outcomes after ophthalmic surgical interventions without any significant complications. CONCLUSION: The tailored ophthalmic surgical intervention(s) provides satisfactory restoration of anatomy and functionality of the eye. These children need specific multi-discipline consultations for the holistic management and complete care.

Evidence that alpha blocking is due to increases in system-level oscillatory damping not neuronal population desynchronisation.

The attenuation of the alpha rhythm following eyes-opening (alpha blocking) is among the most robust features of the human electroencephalogram with the prevailing view being that it is caused by changes in neuronal population synchrony. To further study the basis for this phenomenon we use theoretically motivated fixed-order Auto-Regressive Moving-Average (ARMA) time series modelling to study the oscillatory dynamics of spontaneous alpha-band electroencephalographic activity in eyes-open and eyes-closed conditions and its modulation by the NMDA antagonist ketamine. We find that the reduction in alpha-band power between eyes-closed and eyes-open states is explicable in terms of an increase in the damping of stochastically perturbed alpha-band relaxation oscillatory activity. These changes in damping are putatively modified by the antagonism of NMDA-mediated glutamatergic neurotransmission but are not directly driven by changes in input to cortex nor by reductions in the phase synchronisation of populations of near identical oscillators. These results not only provide a direct challenge to the dominant view of the role that thalamus and neuronal population de-/synchronisation have in the genesis and modulation of alpha electro-/magnetoencephalographic activity but also suggest potentially important physiological determinants underlying its dynamical control and regulation.

Eye movements in demyelinating, autoimmune and metabolic disorders.

PURPOSE OF REVIEW: In the last three decades, the use of eye movements and vestibular testing in many neurological disorders has accelerated, primarily because of practical technologic developments. Although the acute vestibular syndrome is a prime example of this progress, more chronic neurologic and systemic disorders have received less attention. We focus here on recent contributions relating vestibular and ocular motor abnormalities in inflammatory, demyelinating, metabolic, and peripheral nervous system disorders RECENT FINDINGS: Vestibular abnormalities have been identified in acute demyelinating neuropathies (AIDP), in novel genetic mutations responsible for CANVAS (cerebellar ataxia, neuropathy vestibular areflexia syndrome), and in other inherited neuropathies (variants of Charcot-Marie-Tooth disease). In addition, there are differentiating characteristics between the most common CNS demyelinating disorders: multiple sclerosis and neuromyelitis optica (NMO). We summarize new information on Vitamin D metabolism in benign paroxysmal positional vertigo (BPPV), followed by a brief review of the vestibular and ocular motor findings in Wernicke's encephalopathy. We conclude with findings in several paraneoplastic/autoimmune disorders. SUMMARY: This literature review highlights the impact of a careful vestibular and ocular motor evaluation in common neurologic disorder, not only for the initial diagnosis but also for monitoring disease and rehabilitation. A careful examination of eye movements and vestibular function, supplemented with new video techniques to quantify the findings, should be part of the standard neurologic examination.

Less imageable words lead to more looks to blank locations during memory retrieval.

People revisit spatial locations of visually encoded information when they are asked to retrieve that information, even when the visual image is no longer present. Such "looking at nothing" during retrieval is likely modulated by memory load (i.e., mental effort to maintain and reconstruct information) and the strength of mental representations. We investigated whether words that are more difficult to remember also lead to more looks to relevant, blank locations. Participants were presented four nouns on a two by two grid. A number of lexico-semantic variables were controlled to form high-difficulty and low-difficulty noun sets. Results reveal more frequent looks to blank locations during retrieval of high-difficulty nouns compared to low-difficulty ones. Mixed-effects modelling demonstrates that imagery-related semantic factors (imageability and concreteness) predict looking at nothing during retrieval. Results provide the first direct evidence that looking at nothing is modulated by word difficulty and in particular, word imageability. Overall, the research provides substantial support to the integrated memory account for linguistic stimuli and looking at nothing as a form of mental imagery.

Interhemispherically dynamic representation of an eye movement-related activity in mouse frontal cortex.

Cortical plasticity is fundamental to motor recovery following cortical perturbation. However, it is still unclear how this plasticity is induced at a functional circuit level. Here, we investigated motor recovery and underlying neural plasticity upon optogenetic suppression of a cortical area for eye movement. Using a visually-guided eye movement task in mice, we suppressed a portion of the secondary motor cortex (MOs) that encodes contraversive eye movement. Optogenetic unilateral suppression severely impaired contraversive movement on the first day. However, on subsequent days the suppression became inefficient and capability for the movement was restored. Longitudinal two-photon calcium imaging revealed that the regained capability was accompanied by an increased number of neurons encoding for ipsiversive movement in the unsuppressed contralateral MOs. Additional suppression of the contralateral MOs impaired the recovered movement again, indicating a compensatory mechanism. Our findings demonstrate that repeated optogenetic suppression leads to functional recovery mediated by the contralateral hemisphere.

The hippocampus as a visual area organized by space and time: A spatiotemporal similarity hypothesis.

The hippocampus is the canonical memory system in the brain and is not typically considered part of the visual system. Yet, it sits atop the ventral visual stream and has been implicated in certain aspects of vision. Here I review the place of the hippocampal memory system in vision science. After a brief primer on the local circuity, external connectivity, and computational functions of the hippocampus, I explore what can be learned from each field about the other. I first present four areas of vision science (scene perception, imagery, eye movements, attention) that challenge our current understanding of the hippocampus in terms of its role in episodic memory. In the reverse direction, I leverage this understanding to inform vision science in other ways, presenting a working hypothesis about a unique form of visual representation. This spatiotemporal similarity hypothesis states that the hippocampus represents objects according to whether they co-occur in space and/or time, and not whether they look alike, as elsewhere in the visual system. This tuning may reflect hippocampal mechanisms of pattern separation, relational binding, and statistical learning, allowing the hippocampus to generate visual expectations to facilitate search and recognition.

On EMDR: Measuring the working memory taxation of various types of eye (non-)movement conditions.

BACKGROUND AND OBJECTIVE: A recent, large randomized controlled trial employing different forms of eye (non-)movements in eye movement desensitization and reprocessing (EMDR) showed that fixating the eyes either on a therapist's moving or non-moving hand led to equal reductions in symptoms of post-traumatic stress disorder (PTSD). However, numerous EMDR lab analogue studies found that eye movements produce larger memory effects than eyes stationary. These beneficial effects are typically explained by differences in working memory (WM) taxation. We tested the degree of WM taxation of several eye (non-)movement conditions used in the clinical trial. METHODS: All participants (N = 40) performed: (1) eyes moving by following the experimenter's moving finger, (2) eyes fixed on the experimenter's stationary finger, (3) eyes closed, or (4) looking unfocused into the room. Simultaneously they performed a simple reaction time task. Reaction times are an objective index of the extent to which different dual attention tasks tax WM. RESULTS: Eyes moving is more taxing than eyes fixed, while eyes fixed did not differ from eyes unfocused. All conditions were more taxing than eyes closed. LIMITATIONS: We studied WM taxation in a laboratory setting; no clinical interventions were applied. CONCLUSIONS: In line with previous lab studies, making eye movements was more taxing than eyes fixed. We discuss why this effect was not observed for reductions in PTSD symptoms in the clinical trial (e.g., differences in dependent variables, sample population, and intervention duration). For more comprehensive future insights, we recommend integration of mechanistically focused lab analogue studies and patient-oriented clinical studies.

Corollary Discharge for Action and Cognition.

In motor systems, a copy of the movement command known as corollary discharge is broadcast to other regions of the brain to warn them of the impending movement. The premise of this review is that the concept of corollary discharge may generalize in revealing ways to the brain's cognitive systems. An oculomotor pathway from the brain stem to frontal cortex provides a well-established example of how corollary discharge is instantiated for sensorimotor processing. Building on causal evidence from inactivation of the pathway, we motivate forward models as a tool for understanding the contributions of corollary discharge to perception and movement. Finally, we extend the definition of corollary discharge to account for signals that may be used for cognitive forward models of decision making. This framework may provide new insights into signals and circuits that contribute to sequential decision processes, the breakdown of which may account for some symptoms of psychiatric disorders.

Shared neural underpinnings of multisensory integration and trial-by-trial perceptual recalibration in humans.

Perception adapts to mismatching multisensory information, both when different cues appear simultaneously and when they appear sequentially. While both multisensory integration and adaptive trial-by-trial recalibration are central for behavior, it remains unknown whether they are mechanistically linked and arise from a common neural substrate. To relate the neural underpinnings of sensory integration and recalibration, we measured whole-brain magnetoencephalography while human participants performed an audio-visual ventriloquist task. Using single-trial multivariate analysis, we localized the perceptually-relevant encoding of multisensory information within and between trials. While we found neural signatures of multisensory integration within temporal and parietal regions, only medial superior parietal activity encoded past and current sensory information and mediated the perceptual recalibration within and between trials. These results highlight a common neural substrate of sensory integration and perceptual recalibration, and reveal a role of medial parietal regions in linking present and previous multisensory evidence to guide adaptive behavior.

Topical Anesthesia in Children With Intraoperative Adjustable Strabismus Surgery.

PURPOSE: To evaluate strabismus surgery with intraoperative adjustment of sutures under topical anesthesia in children. METHODS: Nineteen children with horizontal deviation underwent a one-stage surgical technique performed under topical anesthesia. Surgery consisted of unilateral or bilateral recession and/or resection of horizontal muscles or the medial or lateral rectus muscles, with intraoperative adjustment of sutures based on alternate prism cover test. Follow-up was done at 1 day and 1, 3, and 6 months postoperatively. RESULTS: Mean age at surgery was 12.68 ± 2.50 years (range: 8 to 16 years). Mean preoperative angle of deviation was 24.21 ± 11.20 prism diopters (PD) (range: -50 to +30 PD) at distance. Mean postoperative angle of deviation at 6 months was 4.11 ± 2.87 PD (range: -10 to +10 PD) at distance. In esotropic patients, the average angle of deviation decreased from +23.80 ± 5.89 PD preoperatively to +4.80 ± 3.35 PD at 6 months, whereas in exotropic patients it decreased from -24.36 ± 12.76 to -3.86 ± 2.77 PD. Seventeen of 19 patients (89%) remained comfortable during surgery, whereas 2 needed an intravenous injection of propofol. The success rate, defined by a postoperative residual angle of deviation of ±8 PD or less, was 89% at 6 months. CONCLUSIONS: Strabismus surgery with intraoperative suture adjustment under topical anesthesia in children is a tolerable procedure with encouraging outcomes, representing an alternative to general anesthesia in well-selected children. Clinical evaluation of children and parents is fundamental to predict a likely poor collaboration of the child during surgery, which, if present, would require surgery under general anesthesia. [J Pediatr Ophthalmol Strabismus. 2019;56(3):173-177.].

No evidence for the inverted U-Curve: More demanding dual tasks cause stronger aversive memory degradation.

BACKGROUND AND OBJECTIVES: Simultaneously making eye movements and recalling a memory leads to competition in working memory (WM), which reduces memory vividness and emotionality. The dose-response relationship between WM taxation and aversive memory degradation is predicted to be either linear (i.e., more cognitively demanding tasks exhibit stronger effects) or follow an inverted U-curve (i.e., there should not be too little, but also not too much taxation). METHODS: Participants (N = 44) recalled four aversive autobiographical memories under four conditions that differed in WM taxation: complex, intermediate, simple, or no counting. Before and after each intervention, and at 24 h follow-up, participants recalled the aversive memory and rated it on vividness and unpleasantness. Using a Bayesian approach the linear and inverted U-shape relationships were directly compared. RESULTS: Pretest to posttest drops in vividness and unpleasantness became larger with increased WM taxation of the counting conditions. There was no support for either hypotheses from pretest to follow-up for memory unpleasantness, whereas for memory vividness anecdotal evidence was found for a linear relationship. LIMITATIONS: A reaction time (RT) task was used to select counting tasks of varying difficulties. However, the validity of this task appears to be compromised under very strenuous conditions. Higher levels of WM taxation might have been possible with more difficult counting tasks. CONCLUSIONS: There is strong evidence for a linear dose-response relationship between WM taxation and memory degradation immediately after the intervention, and some unconvincing evidence for this pattern one day later. There was no evidence for an inverted U-curve.

EEG Artifacts Handling in a Real Practical Brain-Computer Interface Controlled Vehicle.

One of the main issues restricting the practical efficiency of brain-computer interface (BCI) systems is the inevitable occurrence of physiological artifacts during electroencephalography (EEG) recordings. The effects of the artifacts are, however, mostly discarded in practical BCI systems, due to the time-consuming and complicated computational processes. This paper presents the influences of the artifacts and the efficiency of reducing these influences in a practical BCI. Ocular and muscular artifacts are considered due to the high-amplitude and frequent presence. The paradigm is designed based on the mental controlling of a radio-control (RC) car. Two motor imagery commands, containing the imagination of movement of left/right hand, are used to navigate the BCI-based RC car to turn left/right. The results indicate that the artifacts can highly affect the system performance; reducing their influence significantly improves the efficiency.

Treating repetitive suicidal intrusions using eye movements: study protocol for a multicenter randomized clinical trial.

BACKGROUND: Suicide is a major public health problem, and it remains unclear which processes link suicidal ideation and plans to the act of suicide. Growing evidence shows that the majority of suicidal patients diagnosed with major depression or bipolar disorder report repetitive suicide-related images and thoughts (suicidal intrusions). Various studies showed that vividness of negative as well as positive intrusive images may be reduced by dual task (e.g. eye movements) interventions taxing the working memory. We propose that a dual task intervention may also reduce frequency and intensity of suicidal imagery and may be crucial in preventing the transition from suicidal ideation and planning to actual suicidal behaviour. This study aims a) to evaluate the effectiveness of an Eye Movement Dual Task (EMDT) add-on intervention targeting suicidal imagery in depressed patients, b) to explore the role of potential moderators and mediators in explaining the effect of EMDT, and c) to evaluate the cost-effectiveness of EMDT. METHODS: We will conduct a multi-center randomized clinical trial (RCT) evaluating the effects of EMDT in combination with usual care (n = 45) compared to usual care alone (n = 45). Participants will fill in multiple online batteries of self-report questionnaires as well as complete a semi-structured interview (Intrusion Interview), and online computer tasks. The primary outcome is the frequency and intrusiveness of suicidal imagery. Furthermore, the vividness, emotionality, and content of the suicidal intrusions are evaluated; secondary outcomes include: suicidal behaviour and suicidal ideation, severity of depression, psychological symptoms, rumination, and hopelessness. Finally, potential moderators and mediators are assessed. DISCUSSION: If proven effective, EMDT can be added to regular treatment to reduce the frequency and vividness of suicidal imagery. TRIAL REGISTRATION: The study has been registered on October 17th, 2018 at the Netherlands Trial Register, part of the Dutch Cochrane Centre ( NTR7563 ).

To integrate or not to integrate: Temporal dynamics of hierarchical Bayesian causal inference.

To form a percept of the environment, the brain needs to solve the binding problem-inferring whether signals come from a common cause and are integrated or come from independent causes and are segregated. Behaviourally, humans solve this problem near-optimally as predicted by Bayesian causal inference; but the neural mechanisms remain unclear. Combining Bayesian modelling, electroencephalography (EEG), and multivariate decoding in an audiovisual spatial localisation task, we show that the brain accomplishes Bayesian causal inference by dynamically encoding multiple spatial estimates. Initially, auditory and visual signal locations are estimated independently; next, an estimate is formed that combines information from vision and audition. Yet, it is only from 200 ms onwards that the brain integrates audiovisual signals weighted by their bottom-up sensory reliabilities and top-down task relevance into spatial priority maps that guide behavioural responses. As predicted by Bayesian causal inference, these spatial priority maps take into account the brain's uncertainty about the world's causal structure and flexibly arbitrate between sensory integration and segregation. The dynamic evolution of perceptual estimates thus reflects the hierarchical nature of Bayesian causal inference, a statistical computation, which is crucial for effective interactions with the environment.