Immersive virtual reality gameplay detects visuospatial atypicality, including unilateral spatial neglect, following brain injury: a pilot study.

BACKGROUND: In neurorehabilitation, problems with visuospatial attention, including unilateral spatial neglect, are prevalent and routinely assessed by pen-and-paper tests, which are limited in accuracy and sensitivity. Immersive virtual reality (VR), which motivates a much wider (more intuitive) spatial behaviour, promises new futures for identifying visuospatial atypicality in multiple measures, which reflects cognitive and motor diversity across individuals with brain injuries. METHODS: In this pilot study, we had 9 clinician controls (mean age 43 years; 4 males) and 13 neurorehabilitation inpatients (mean age 59 years; 9 males) recruited a mean of 41 days post-injury play a VR visual search game. Primary injuries included 7 stroke, 4 traumatic brain injury, 2 other acquired brain injury. Three patients were identified as having left sided neglect prior to taking part in the VR. Response accuracy, reaction time, and headset and controller raycast orientation quantified gameplay. Normative modelling identified the typical gameplay bounds, and visuospatial atypicality was defined as gameplay beyond these bounds. RESULTS: The study found VR to be feasible, with only minor instances of motion sickness, positive user experiences, and satisfactory system usability. Crucially, the analytical method, which emphasized identifying 'visuospatial atypicality,' proved effective. Visuospatial atypicality was more commonly observed in patients compared to controls and was prevalent in both groups of patients-those with and without neglect. CONCLUSION: Our research indicates that normative modelling of VR gameplay is a promising tool for identifying visuospatial atypicality after acute brain injury. This approach holds potential for a detailed examination of neglect.

Methodological weakness of the death-word-fragment task: Alternative implicit death anxiety measures.

The efficacy of different implicit death anxiety measures was examined. In Study 1 (N = 133), the death-word-fragment task (DWFT), commonly used to test death-thought accessibility in terror management theory (TMT) research, did not differentiate between mortality salience (MS) and control conditions. Instead, death-related word completions were associated with word dimensions other than MS induction. Study 2 (N = 155) tested three implicit measures (lexical-decision task, dot-probe task, ambiguous pictures task), which differentiated between conditions, revealing greater sensitivity than the DWFT. As TMT research widens its scope, investigating measures to capture implicit death concerns is important.

The Impact of Older Age and Sex on Motion Discrimination.

Background/Study Context: Reports of age-related differences on motion discrimination tasks have produced inconsistent findings concerning the influence of sex. Some studies have reported that older women have higher thresholds than older men, with others finding that women have higher motion thresholds regardless of age group. Reports of the age at which declines in motion discrimination first occur also differ, with some studies reporting declines only in groups aged over 70 years, with others reporting that age-related decline occurs at a younger age. The current study aimed to determine whether the sex differences found occur because relative to men, women have greater difficulty extracting motion signals from noise (Experiment 1) or have greater difficulty making use of the available motion cues (Experiment 2) in these complex moving stimuli. In addition, the influence of these manipulations on groups aged under and over 70 years was explored. METHODS: Motion discrimination measures were obtained using 39 older adults aged between 60 and 85 years (21 women) and 40 younger adults aged between 20 and 45 years (20 women). In Experiment 1, coherent motion and relative motion displacement thresholds were obtained. In Experiment 2, coherent motion thresholds were obtained for stimuli containing either 150 or 600 dots. RESULTS: In Experiment 1, the older group had significantly higher thresholds on the relative motion displacement and coherent motion tasks than a younger group. No differences in motion sensitivity were found in the older groups aged under or over 70 years. Women regardless of age group had significantly higher thresholds than men on both tasks. In Experiment 2, the older group had higher coherence thresholds than the younger group, and the number of dots presented had no influence on thresholds, for the older group or older women specifically. In the younger group, women had higher coherence thresholds than men with presentation of 150 but not 600 dots. There were 51% of the older group who showed evidence of age-related decline on all the motion coherence tasks conducted, with half of these in each the group aged under and over 70 years. CONCLUSION: Difficulties with noise exclusion failed to explain the sex differences found. The increased number of motion cues present when a larger number of dots were included was sufficient to reduce coherence thresholds in younger women but not older men or women. In addition to age, developmental history and sex may provide further predictors in older individuals of decline on measures of motion discrimination.

Fundamental differences between perception and cognition aside from cognitive penetrability.

Fundamental differences between perception and cognition argue that the distinction can be maintained independently of cognitive penetrability. The core processes of cognition can be integrated under the theory of relational knowledge. The distinguishing properties include symbols and an operating system, structure-consistent mapping between representations, construction of representations in working memory that enable generation of inferences, and different developmental time courses.

Population-based estimated reference creatinine values: a novel method of a robust electronic acute kidney injury alert system.

BACKGROUND: Acute kidney injury (AKI) is common in hospitalized patients. Despite the progress that has been made in the last decade, early identification of AKI cases remains a challenge. In recent years, electronic AKI alert (e-AKI alert) systems have been tested and are usually based on changes in serum creatinine (Cr) values. However, these methods do not include one of the common scenarios, i.e. when there is no available preadmission Cr value available for a patient to compare and hence an e-AKI alert cannot be issued. Therefore, it is essential to have an alternative algorithm to produce e-AKI alerts in such scenarios. METHOD: We have developed e-AKI alert algorithms which compare serum Cr values at presentation with previous results, within KDIGO AKI guideline-specified classifications. However, where a comparator is not available, we have produced a 'population-based reference Cr value' age and sex matched from 137,000 serum Cr values extracted from blood tests in general practice from our Telepath system. RESULTS: Cr results were split by gender, and then within each group the Cr were stratified according to year of age. The median Cr for each individual year of age was identified and plotted versus age to give separate graphs for males and females that gave excellent fits (R(2)) to cubic regressions. CONCLUSION: Population-based estimated reference Cr measurements from community blood test results is a more robust method of baseline Cr value estimation in generating potential e-AKI alerts to help early recognition and treatment of AKI cases leading to improved outcome.

Color and spatial frequency are related to visual pattern sensitivity in migraine.

OBJECTIVE: To assess the potential for particular colors to alleviate visual discomfort when people with migraine view repetitive geometric or striped patterns. BACKGROUND: Visual stimuli, such as flicker, glare, or stripes, can trigger migraine and headache. They can also elicit feelings of discomfort and aversion. There are reports that color can be used to decrease the experience of discomfort and reduce migraine frequency. DESIGN/METHODS: Five sets of striped patterns (3, 12 cycles per degree [cpd]) were created using cardinal colors tailored to selectively stimulate the early visual pathways: achromatic (black/white), tritan (black/purple, black/yellow), protan/deutan (black/red, black/green). All had the same high luminance contrast (0.9 Michelson contrast). Twenty-eight migraine (14 migraine with aura, 14 migraine without aura) and 14 control participants rated the discomfort and described the distortions seen in these patterns. They were also assessed for visual migraine/headache triggers, contrast sensitivity, color vision, acuity, stereopsis, visual discomfort from reading, and dyslexia. RESULTS: In the migraine groups, a comparable number of illusions were seen with the 3 and 12 cpd achromatic gratings, whereas in the control group the greatest number was seen with the 3 cpd grating. In the migraine groups only, all 4 colors reduced, to some extent, the number of illusions and 2 decreased the discomfort, particularly for the 12 cpd gratings. There were significant group differences for contrast sensitivity, reported visual migraine/headache triggers, and the visual discomfort scale. There were a few significant correlations between the different measures, notably between the achromatic visual discomfort measures and reports of visual migraine triggers. CONCLUSIONS: Color, independent of luminance or particular color contrasts, can have therapeutic effects for people with visually triggered migraine as it can reduce the number of perceived illusions when viewing stripes or text. The effect was not color-specific and was greatest for the 12 cpd gratings. Given the significant associations between the achromatic discomfort measures and reports of visual triggers, and the lack of significant associations between the chromatic discomfort measures and reports of visual triggers, further research is recommended to explore the potential to reduce the number of visually triggered migraines with color in addition to alleviating visual discomfort.

Reducing magnocellular processing of various motion trajectories tests single process theories of visual position perception.

Spatial projection and temporal integration are two prominent theories of visual localization for moving stimuli which gain most of their explanatory power from a single process. Spatial projection theories posit that a moving stimulus' perceived position is projected forwards in order to compensate for processing delays (Eagleman & Sejnowski, 2007; Nijhawan, 2008). Temporal integration theories (Krekelberg & Lappe, 2000) suggest that an averaging over positions occupied by the moving stimulus for a period of time is the dominant process underlying perception of position. We found that when magnocellular (M) pathway processing was reduced, there were opposite effects on localization judgments when a smooth, continuous trajectory was used, compared to when the moving object suddenly appeared, or suddenly reversed direction. The flash-lag illusion was decreased for the continuous trajectory, but increased for the onset and reversal trajectories. This cross-over interaction necessitates processes additional to those proposed by either the spatial projection or temporal integration theories in order to explain the perception of the position of moving stimuli across all our conditions. Differentiating our onset trajectory conditions from a Fröhlich illusion, in a second experiment, we found a null Fröhlich illusion under normal luminance-defined conditions, significantly smaller than the corresponding flash-lag illusion, but significantly increased when M processing was reduced. Our data are most readily accounted for by Kirschfeld and Kammer's (1999) backward-inhibition and focal attention theory.

The attention atlas virtual reality platform maps three-dimensional (3D) attention in unilateral spatial neglect patients: a protocol.

BACKGROUND: Deficits in visuospatial attention, known as neglect, are common following brain injury, but underdiagnosed and poorly treated, resulting in long-term cognitive disability. In clinical settings, neglect is often assessed using simple pen-and-paper tests. While convenient, these cannot characterise the full spectrum of neglect. This protocol reports a research programme that compares traditional neglect assessments with a novel virtual reality attention assessment platform: The Attention Atlas (AA). METHODS/DESIGN: The AA was codesigned by researchers and clinicians to meet the clinical need for improved neglect assessment. The AA uses a visual search paradigm to map the attended space in three dimensions and seeks to identify the optimal parameters that best distinguish neglect from non-neglect, and the spectrum of neglect, by providing near-time feedback to clinicians on system-level behavioural performance. A series of experiments will address procedural, scientific, patient, and clinical feasibility domains. RESULTS: Analyses focuses on descriptive measures of reaction time, accuracy data for target localisation, and histogram-based raycast attentional mapping analysis; which measures the individual's orientation in space, and inter- and intra-individual variation of visuospatial attention. We will compare neglect and control data using parametric between-subjects analyses. We present example individual-level results produced in near-time during visual search. CONCLUSIONS: The development and validation of the AA is part of a new generation of translational neuroscience that exploits the latest advances in technology and brain science, including technology repurposed from the consumer gaming market. This approach to rehabilitation has the potential for highly accurate, highly engaging, personalised care.

Motion processing deficits in migraine are related to contrast sensitivity.

BACKGROUND: There are conflicting reports concerning the ability of people with migraine to detect and discriminate visual motion. Previous studies used different displays and none adequately assessed other parameters that could affect performance, such as those that could indicate precortical dysfunction. METHODS: Motion-direction detection, discrimination and relative motion thresholds were compared from participants with and without migraine. Potentially relevant visual covariates were included (contrast sensitivity; acuity; stereopsis; visual discomfort, stress, triggers; dyslexia). RESULTS: For each task, migraine participants were less accurate than a control group and had impaired contrast sensitivity, greater visual discomfort, visual stress and visual triggers. Only contrast sensitivity correlated with performance on each motion task; it also mediated performance. CONCLUSIONS: Impaired performance on certain motion tasks can be attributed to impaired contrast sensitivity early in the visual system rather than a deficit in cortical motion processing per se. There were, however, additional differences for global and relative motion thresholds embedded in noise, suggesting changes in extrastriate cortex in migraine. Tasks to study the effects of noise on performance at different levels of the visual system and across modalities are recommended. A battery of standard visual tests should be included in any future work on the visual system and migraine.

Pattern-Induced Visual Discomfort and Anxiety in Migraineurs: Their Relationship and the Effect of Colour.

In migraineurs, coloured lenses were found to reduce the visual stress caused by an aversive pattern known to trigger migraines by 70%, but do such patterns also produce a low-level anxiety/fear response? Is this response lessened by colour? We sought to investigate this in a study comprising a broad screening component followed by a dot-probe experiment to elicit attentional biases (AB) to aversive patterns. Undergraduate psychology students completed headache and visual discomfort (VD) questionnaires (N = 358), thereby forming a subject pool from which 13 migraineurs with high visual discomfort and 13 no-headache controls with low visual discomfort, matched on age and sex, completed a dot-probe experiment. Paired stimuli were presented for 500 ms: aversive achromatic 3 cpd square wave gratings vs control, scrambled patterns. These conditions were repeated using the colour that was most comfortable for each participant. VD was greater in the more severe headache groups. On all measures, the migraineurs were more anxious than the controls, and a positive relationship was found between VD and trait anxiety. The 3 cpd gratings elicited an aversive AB in the migraine group which was somewhat reduced by the use of colour, and this was not seen in the controls. The results suggest a new role for colour in reducing visual stress via anxiety/fear reduction.

An investigation into the use of recorded music as a surgical intervention: A systematic, critical review of methodologies used in recent adult controlled trials.

CONTEXT: While music is being increasingly used as a surgical intervention, the types of music used and the reasons underlying their selection remain inconsistent. Empirical research into the efficacy of such musical interventions is therefore problematic. OBJECTIVE: To provide clear guidelines for musical selection and employment in surgical interventions, created through a synthesis of the literature. The aim is to examine how music is implemented in surgical situations, and to provide guidance for the selection and composition of music for future interventions. METHODS: English language quantitative surgical intervention studies from Science Direct, ProQuest, and Sage Journals Online, all published within the last 10 years and featuring recorded music, were systematically reviewed. Variables investigated included: the time the intervention was performed, the intervention length, the outcomes targeted, music description (general and specific), theoretical frameworks underlying the selection of the music, whether or not a musical expert was involved, participant music history, and the participants' feedback on the chosen music. RESULTS: Several aspects contribute to the lack of scientific rigour regarding music selection in this field, including the lack of a theoretical framework or frameworks, no involvement of musical experts, failure to list the music tracks used, and the use of vague and subjective terms in general music descriptions. Patients are frequently allowed to select music (risking both choosing music that has an adverse effect and making study replication difficult), and patient music history and listening habits are rarely considered. Crucially, five primary theoretical frameworks underlying the effectiveness of music arose in the literature (distraction, relaxation, emotional shift, entrainment, and endogenous analgesia), however music was rarely selected to enhance any of these mechanisms. CONCLUSIONS: Further research needs to be conducted to ensure that music is selected according to a theoretical framework and more rigorous and replicable methodology. Music interventions can be made more effective at improving psychological states and reducing physiological arousal by selecting music conducive to specific mechanisms, and also by considering at what point during the surgical experience the music would be most effective. Greater involvement of music experts in interventions would help to ensure that the most appropriate music was chosen, and that it is clearly and precisely described.

General practitioner (GP) cardiac troponin test requesting: findings from a clinical laboratory audit.

BACKGROUND: There is limited data and literature on the issue of cardiac troponin test requesting by general practitioners (GPs). It was therefore our aim to audit the cardiac troponin test requests made by GPs in our community with a view to develop an informed strategy for assay provision and reporting of results. METHODS: A retrospective audit was undertaken of data in our laboratory database for all cardiac troponin T (cTnT) tests requested by GPs between January and June 2005. A prospective audit was then carried out between July and December 2005 using the telephone interview method. The number and distribution of tests, the reasons for the request and the intended action by the GPs were quantified. RESULTS: Forty-five of 46 of the results of both the retrospective and prospective audits were negative based on the 99th percentile level with less than 10% imprecision (cTnT <0.03 microg/L). During the one-year study period, we had requests from 24 general practices with a mean and mode of two and one requests per general practice respectively. The most common reason for the request was found to be chest pain that had occurred more than 24 h ago. CONCLUSION: Bearing in mind the limitations of an audit study, our findings obviate the use of cTnT in general practice. We suggest that the laboratory should liase with the GP and advise referral for specialist care if clinical suspicion of acute coronary syndrome is high.

Reflexive optokinetic nystagmus in younger and older observers under photopic and mesopic viewing conditions.

PURPOSE: To investigate the effect of age on optokinetic nystagmus (OKN) in response to stimuli designed to preferentially stimulate the M-pathway. METHOD: OKN was recorded in 10 younger (32.3 +/- 5.98 years) and 10 older (65.6 +/- 6.53) subjects with normal vision. Vertical gratings of 0.43 or 1.08 cpd drifting at 5 degrees /s or 20 degrees /s and presented at either 8% or 80% contrast were displayed on a large screen as full-field stimulation, central stimulation within a central Gaussian-blurred window of 15 degrees diameter, or peripheral stimulation outside this window. All conditions apart from the high-contrast condition were presented in a random order at two light levels, mesopic (1.8 cdm(-2)) and photopic (71.5 cdm(-2)). RESULTS: Partial-field data indicated that central stimulation, mesopic light levels, and lower temporal frequency each significantly increased slow-phase velocity (SPV). Although there was no overall difference between groups for partial-field stimulation, full-field stimulation, or low-contrast stimulation, a change in illumination revealed a significant interaction with age: there was a larger decrease in SPV going from photopic to mesopic conditions for the older group than the younger group, especially for higher temporal frequency stimulation. CONCLUSIONS: OKN becomes reflexive in conditions conducive to M-pathway stimulation, and this rOKN response is significantly diminished in older healthy adults than in younger healthy adults, indicative of decreased M-pathway sensitivity.

Attention 'capture' by the flash-lag flash.

We report data from eight participants who made alignment judgements between a moving object and a stationary, continuously visible 'landmark'. A reversing object had to overshoot the landmark by a significant amount in order to appear to reverse aligned with it. In addition, an adjacent flash irrelevant to the judgment task reliably increased this illusory 'foreshortening'. This and other results are most simply explained by a model in which the flash causes attentional capture, complemented by processes of temporal integration, or backward inhibition, and object representation. A flash used to probe the perception of a moving object's position disrupts that very perception.

Events before the flash Do influence the flash-lag magnitude.

The flash-lag effect occurs when a flash abreast of a smoothly moving object is perceived to spatially lag the moving object. The postdiction accounts of this effect assume either that the flash "resets" motion detectors [Science 287 (2000) 2036], or that position information is not computed for moving objects until it is needed [Trends in the Neurosciences 25 (2002) 293], the latter view having also been proposed by Brenner and Smeets [Vision Research 40 (2000) 1645]. According to these accounts, events occurring before the flash should not change the magnitude of the flash-lag effect. In our experiment, pre-exposure of the moving object as a stationary stimulus, for as little as 50 ms before the flash occurred, significantly reduced the flash-lag effect.

The influence of attention and target identification on saccadic eye movements depends on prior target location.

Saccadic latency is reduced by a temporal gap between fixation point and target, by identification of a target feature, and by movement in a new direction (inhibition of saccadic return, ISR). A simple additive model was compared with a shared resources model that predicts a three-way interaction. Twenty naïve participants made horizontal saccades to targets left and right of fixation in a randomised block design. There was a significant three-way interaction among the factors on saccade latency. This was revealed in a two-way interaction between feature identification and the gap versus no gap factor which was only apparent when the saccade was in the same direction as the previous saccade. No interaction was apparent when the saccade was in the opposite direction. This result supports an attentional inhibitory effect that is present during ISR to a previous location which is only partly released by the facilitative effect of feature identification and gap. Together, anticipatory error data and saccade latency interactions suggest a source of ISR at a higher level of attention, possibly localised in the dorsolateral prefrontal cortex and involving tonic activation.

Effect of motion smoothness on the flash-lag illusion.

Two flash-lag experiments were performed in which the moving object was flashed in a succession of locations creating apparent motion and the inter-stimulus distance (ISD) between those locations was varied. In the first (n=10), the size of the flash-lag illusion was a declining non-linear function of the ISD and the largest reduction in its magnitude corresponded closely to the value where observers judged the continuity of optimal apparent motion to be lost. In the second (n=11) with large ISDs, we found the largest illusions when the flash initiated the movement, and no effect was observed when the flash terminated the movement. The data support motion position biasing or temporal integration accounts of the illusion with processing predominantly based on motion after the flash.

The use of virtual reality in acrophobia research and treatment.

Acrophobia, or fear of heights, is a widespread and debilitating anxiety disorder affecting perhaps 1 in 20 adults. Virtual reality (VR) technology has been used in the psychological treatment of acrophobia since 1995, and has come to dominate the treatment of numerous anxiety disorders. It is now known that virtual reality exposure therapy (VRET) regimens are highly effective for acrophobia treatment. This paper reviews current theoretical understanding of acrophobia as well as the evolution of its common treatments from the traditional exposure therapies to the most recent virtually guided ones. In particular, the review focuses on recent innovations in the use of VR technology and discusses the benefits it may offer for examining the underlying causes of the disorder, allowing for the systematic assessment of interrelated factors such as the visual, vestibular and postural control systems.

The phenomenon of seasonal pseudohypokalemia: effects of ambient temperature, plasma glucose and role for sodium-potassium-exchanging-ATPase.

OBJECTIVES: There is limited data regarding the phenomenon of seasonal pseudohypokalemia. We aimed to demonstrate the incidence of spurious hypokalemia during the summer months and to investigate the mechanism of cause. DESIGN AND METHODS: Potassium and glucose results from primary care and hospital patients were collected retrospectively for a period of 1 year to assess the incidence of pseudohypokalemia. Experiments were undertaken to confirm that this was a reversible in vitro phenomenon due to increased temperature mediated by sodium-potassium-exchanging-ATPase. RESULTS: Our data show an increased incidence of hypokalemia associated with increasing ambient temperature during June-August in samples from primary care but not in hospital samples. In a subset of patients, we showed that the repeat results were within or at the lower limit of the reference range. Experiments showed that this phenomenon was mediated by the sodium-potassium-exchanging-ATPase. CONCLUSIONS: There is an increased incidence of pseudohypokalemia during the summer (seasonal pseudohypokalemia) in samples from primary care and this is an in vitro pseudo-phenomenon mediated by sodium-potassium-exchanging-ATPase.

The role of self-motion in acrophobia treatment.

Acrophobia is a chronic, highly debilitating disorder preventing sufferers from engaging with high places. Its etiology is linked to the development of mobility during infancy. We evaluated the efficacy of various types of movement in the treatment of this disorder within a virtual reality (VR) environment. Four men and four women who were diagnosed with acrophobia were tested in a virtual environment reproducing the balcony of a hotel. Anxiety and behavioral avoidance measures were taken as participants climbed outdoor stairs, moved sideways on balconies, or stood still. This took place in both real and virtual environments as part of a treatment evaluation study. Participants experienced an elevated level of anxiety not only to increases in height but also when required to move laterally at a fixed height. These anxiety levels were significantly higher than those elicited by viewing the fear-invoking scene without movement. We have demonstrated a direct link between any type of movement at a height and the triggering of acrophobia in line with earlier developmental studies. We suggest that recalibration of the action-perception system, aided by VR, can be an important adjunct to standard psychotherapy.