Optometry and Vision Sciences - Research Publications
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ItemNo Preview AvailableOptimising visual attention in children with autism spectrum disorder: a comparison of fixation distributions viewing singing and speech(Association for Research in Vision and Ophthalmology, 2017-06-01)Purpose : Many children with autism spectrum disorder (ASD) are at risk of social isolation and limited social development due to difficulties with gaze and visual attention to people. Studies have shown that children with ASD may prefer music to other stimuli. We hypothesised that a short video of a singer would elicit more attention to the performer, particularly to her face, than a video of her reading a story and that the child’s familiarity with the song and story would enhance attention. Methods : 16 children aged 7-10 (14 M, 2 F) with ASD took part. Stimuli were 4 videos 1 minute long. Content was a favourite song or story of the child, along with a song and story which were the same for all children. The performer, her clothing, lighting and sound level were the same across tasks. Props were a pair of drums for the songs and a storybook of similar size for the stories. Eye movements were recorded with an Eyelink 1000; areas of interest (AOIs) were defined for the face, prop and body. 3-way repeated measures ANOVAs were used to examine the proportion of total dwell time, the proportion of total fixations and pupil area for each AOI in each trial. Results : For dwell time proportion, a significant interaction was found for familiarity*AOI (F=7.45, p=.004), with gaze time to the face being increased for familiar trials (Table 1). Similarly, medium*AOI was significant (F=6.01, p=.013), with increased gaze time to the face and body and decreased time to the prop for the songs (Table 2). The same patterns were seen for proportion of fixation counts to the AOIs (familiarity*AOI F=4.97, p =.016; medium*AOI F=10.33, p=.001). For the pupil, only familiarity and AOI were significant; pupils were larger for familiar stimuli (F=16.70, p=.001) and for the face and prop (F=6.8, p=.015), with the body eliciting less dilation. Conclusions : As hypothesised, the videos of singing attracted children's gaze to the performer more than did those of her reading a story. Familiarity with the material being performed also attracted more attention to her face. Familiarity and gaze to the face also increased arousal, as indexed by pupil dilation. Observation by children with ASD of a singer, particularly one performing their favourite songs, may be a useful intervention for improving their social engagement skills.
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ItemHigh-definition transcranial direct current stimulation in anorexia nervosa: A pilot study(WILEY, 2019-11)OBJECTIVE: Anorexia nervosa (AN) is a serious psychiatric condition often associated with poor outcomes. Biologically informed treatments for AN, such as brain stimulation, are lacking, in part due to the unclear nature of the neurobiological contributions to the illness. However, recent research has suggested a specific neurobiological target for the treatment of AN, namely stimulation of the inferior parietal lobe (IPL). The aim of this study was to stimulate-noninvasively-the left IPL in individuals with AN using high-definition transcranial direct current stimulation (HD-tDCS). METHOD: Twenty participants will be randomized to receive 10 daily sessions of HD-tDCS or sham HD-tDCS (placebo). Assessments will be carried out at baseline and end point, as well as 4- and 12-week follow-ups. DISCUSSION: This pilot investigation will primarily determine the feasibility and acceptability of this intervention.
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ItemDifferences in regional grey matter volumes in currently ill patients with anorexia nervosa(WILEY, 2018-01)Neurobiological findings in anorexia nervosa (AN) are inconsistent, including differences in regional grey matter volumes. Methodological limitations often contribute to the inconsistencies reported. The aim of this study was to improve on these methodologies by utilising voxel-based morphometry (VBM) analysis with the use of diffeomorphic anatomic registration through an exponentiated lie algebra algorithm (DARTEL), in a relatively large group of individuals with AN. Twenty-six individuals with AN and 27 healthy controls underwent a T1-weighted magnetic resonance imaging (MRI) scan. AN participants were found to have reduced grey matter volumes in a number of areas including regions of the basal ganglia (including the ventral striatum), and parietal and temporal cortices. Body mass index (BMI) and global scores on the Eating Disorder Examination Questionnaire (EDE-Q) were also found to correlate with grey matter volumes in a region of the brainstem (including the substantia nigra and ventral tegmental area) in AN, and predicted 56% of the variance in grey matter volumes in this area. The brain regions associated with grey matter reductions in AN are consistent with regions responsible for cognitive deficits associated with the illness including anhedonia, deficits in affect perception and saccadic eye movement abnormalities. Overall, the findings suggest reduced grey matter volumes in AN that are associated with eating disorder symptomatology.
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ItemAn Overlooked Brain Region in the Aetiology of Anorexia Nervosa: The Importance of Behaviourally Driven Neuroimaging Analysis(SAGE PUBLICATIONS LTD, 2018-12-20)The neurobiological contributions to anorexia nervosa (AN) remain poorly understood, hindering the development of effective neurobiological treatments such as medications and brain stimulation. A large number of studies have been undertaken utilising neuroimaging techniques, such as magnetic resonance imaging (MRI), to gain a better understanding of the brain mechanisms involved in the illness. However, the analyses undertaken by many studies have utilised a whole-brain analytical approach as much of this research has been exploratory in nature. This is, however, problematic as small brain regions that differ between groups may not have the statistical power to produce statistically significant results. This is highlighted in a recent study undertaken by our group utilising diffusion-weighted imaging. In this research, we identified widespread white matter microstructural differences in individuals with AN, but only showed differences in a small brain region (the superior colliculus) when a region-of-interest approach that was driven by behavioural findings was utilised. The importance of hypothesis-driven neuroimaging analyses is discussed in this article.
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ItemLongitudinal assessment of reflexive and volitional saccades in Niemann-Pick Type C disease during treatment with miglustat(BMC, 2015-12-21)BACKGROUND: Niemann-Pick Type C disease (NPC), is an autosomal recessive neurovisceral disorder of lipid metabolism. One characteristic feature of NPC is a vertical supranuclear gaze palsy particularly affecting saccades. However, horizontal saccades are also impaired and as a consequence a parameter related to horizontal peak saccadic velocity was used as an outcome measure in the clinical trial of miglustat, the first drug approved in several jurisdictions for the treatment of NPC. As NPC-related neuropathology is widespread in the brain we examined a wider range of horizontal saccade parameters and to determine whether these showed treatment-related improvement and, if so, if this was maintained over time. METHODS: Nine adult NPC patients participated in the study; 8 were treated with miglustat for periods between 33 and 61 months. Data were available for 2 patients before their treatment commenced and 1 patient was untreated. Tasks included reflexive saccades, antisaccades and self-paced saccades, with eye movements recorded by an infrared reflectance eye tracker. Parameters analysed were reflexive saccade gain and latency, asymptotic peak saccadic velocity, HSEM-α (the slope of the peak duration-amplitude regression line), antisaccade error percentage, self-paced saccade count and time between refixations on the self-paced task. Data were analysed by plotting the change from baseline as a proportion of the baseline value at each test time and, where multiple data values were available at each session, by linear mixed effects (LME) analysis. RESULTS: Examination of change plots suggested some modest sustained improvement in gain, no consistent changes in asymptotic peak velocity or HSEM-α, deterioration in the already poor antisaccade error rate and sustained improvement in self-paced saccade rate. LME analysis showed statistically significant improvement in gain and the interval between self-paced saccades, with differences over time between treated and untreated patients. CONCLUSIONS: Both qualitative examination of change scores and statistical evaluation with LME analysis support the idea that some saccadic parameters are robust indicators of efficacy, and that the variability observed across measures may indicate locally different effects of neurodegeneration and of drug actions.
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ItemSelf perception and facial emotion perception of others in anorexia nervosa(FRONTIERS MEDIA SA, 2015-08-10)BACKGROUND: Whether individuals with anorexia nervosa (AN) are able to accurately perceive emotions from faces of others is unclear. Furthermore, whether individuals with AN process images of their own face differently to healthy individuals has thus far not been investigated. Therefore, the aim of this study was to investigate facial affect processing and the processing of one's own face through measures of emotion identification, functional magnetic resonance imaging (fMRI) and eyetracking. METHODS: Twenty-four females with AN and 25 matched healthy control participants were presented with an implicit emotion processing task during fMRI and eyetracking, followed by an explicit emotion identification task. RESULTS: The AN group were found to 'hyperscan' stimuli and avoided visually attending to salient features of their own face images. RESULTS of the fMRI revealed increased activity to own face stimuli in AN in the right inferior and middle temporal gyri, and right lingual gyrus. AN participants were not found to display emotion identification deficits to the standard emotional face stimuli. DISCUSSION: The findings are discussed in terms of increased anxiety to disorder-relevant stimuli in AN. Potential clinical implications are discussed in relation to the use of eyetracking techniques to improve the perception of self in AN.
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ItemSelf-reported and behavioural impulsivity in anorexia nervosa(BAISHIDENG PUBLISHING GROUP INC, 2016-09-22)AIM: To examine how self-reported and behavioural impulsivity are related in anorexia nervosa (AN). METHODS: Twenty-four females with AN and 25 healthy controls (HC) participant in the study. Self-reported impulsivity was assessed with the Barratt Impulsiveness Scale (BIS-11). The scale yields three second-order factors: Attentional, motor and non-planning. Behavioural impulsivity was investigated with the continuous performance test (CPT), a computer-based task of sustained attention in which numbers are flashed briefly on screen and participants are required to click the mouse when the same number appears consecutively. The rate of commission and omission errors can be used a measure of behavioural imulsivity. RESULTS: AN participants self-reported increased attentional [AN: 20.67 (3.64), HC: 13.88 (2.91), P = 0.001] and reduced motor impulsivity [AN: 11.55 (2.28), HC: 14.08 (2.78), P = 0.002]. The rate of omission or commission errors on the CPT did not differ between groups (P > 0.05). BIS-11 and CPT measures did not significantly correlate, but attentional impulsivity was related to negative mood states in AN (depression: r = 0.52, P = 0.010, anxiety: r = 0.55, P = 0.006, stress: r = 0.57, P = 0.004). CONCLUSION: The discrepancy between self-reported and behavioural impulsivity are discussed in terms of perfectionism in AN. Furthermore, it is suggested that improving negative mood states may resolve this inconsistency in AN.
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ItemSaccadic Eye Movements in Anorexia Nervosa(PUBLIC LIBRARY SCIENCE, 2016-03-24)BACKGROUND: Anorexia Nervosa (AN) has a mortality rate among the highest of any mental illness, though the factors involved in the condition remain unclear. Recently, the potential neurobiological underpinnings of the condition have become of increasing interest. Saccadic eye movement tasks have proven useful in our understanding of the neurobiology of some other psychiatric illnesses as they utilise known brain regions, but to date have not been examined in AN. The aim of this study was to investigate whether individuals with AN differ from healthy individuals in performance on a range of saccadic eye movements tasks. METHODS: 24 females with AN and 25 healthy individuals matched for age, gender and premorbid intelligence participated in the study. Participants were required to undergo memory-guided and self-paced saccade tasks, and an interleaved prosaccade/antisaccade/no-go saccade task while undergoing functional magnetic resonance imaging (fMRI). RESULTS: AN participants were found to make prosaccades of significantly shorter latency than healthy controls. AN participants also made an increased number of inhibitory errors on the memory-guided saccade task. Groups did not significantly differ in antisaccade, no-go saccade or self-paced saccade performance, or fMRI findings. DISCUSSION: The results suggest a potential role of GABA in the superior colliculus in the psychopathology of AN.
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ItemThe influence of action video game playing on eye movement behaviour during visual search in abstract, in-game and natural scenes(SPRINGER, 2017-02)Action game playing has been associated with several improvements in visual attention tasks. However, it is not clear how such changes might influence the way we overtly select information from our visual world (i.e. eye movements). We examined whether action-video-game training changed eye movement behaviour in a series of visual search tasks including conjunctive search (relatively abstracted from natural behaviour), game-related search, and more naturalistic scene search. Forty nongamers were trained in either an action first-person shooter game or a card game (control) for 10 hours. As a further control, we recorded eye movements of 20 experienced action gamers on the same tasks. The results did not show any change in duration of fixations or saccade amplitude either from before to after the training or between all nongamers (pretraining) and experienced action gamers. However, we observed a change in search strategy, reflected by a reduction in the vertical distribution of fixations for the game-related search task in the action-game-trained group. This might suggest learning the likely distribution of targets. In other words, game training only skilled participants to search game images for targets important to the game, with no indication of transfer to the more natural scene search. Taken together, these results suggest no modification in overt allocation of attention. Either the skills that can be trained with action gaming are not powerful enough to influence information selection through eye movements, or action-game-learned skills are not used when deciding where to move the eyes.
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ItemOscillopsia and the Influence of Stress and Motivation in Fusion Maldevelopment Nystagmus Syndrome(ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2013-03)PURPOSE: We examined factors influencing perceptual stability in observers with fusion maldevelopment nystagmus syndrome (FMNS). In addition, we also investigated the effect of visual demand, task-related physiologic stress, and motivation on the nystagmus waveform. METHODS: Perception of oscillopsia during daily activities was assessed via a questionnaire. Perception of oscillopsia in the laboratory was assessed using central and peripheral (10°) light emitting diodes (LEDs) in front of a background display of random, fixed-contrast shapes. Task-induced stress was achieved via a time restricted acuity task with or without concurrent mental arithmetic challenge, and motivation varied using a reward-penalty paradigm. The experiments have been previously described elsewhere. RESULTS: Six out of nine subjects reported experiencing oscillopsia in certain daily activities. in the laboratory, the percentages of trials with perceptions of motion of the led and background were as follows: neither, 60% to 70%; background only, 20% to 30%; both, 5% to 15%, and LED only, 5% to 15%. Over all trials, six of nine experienced oscillopsia for both the low- and high-contrast image respectively (i.e., three subjects never experienced oscillopsia). The background was frequently seen moving for both images regardless of contrast and/or condition. Trials with and without oscillopsia did not differ when comparing foveation. In the second experiment, task-related physiologic stress and motivation were reflected in an increase in heart rate; nystagmus waveform intensity increased and foveation decreased. The magnitude of changes in heart rate was uncorrelated with changes in waveform parameters for all experiments, however. CONCLUSIONS: Preliminary results suggest that the FMNS group does perceive spatially inhomogeneous oscillopsia, similar to infantile nystagmus syndrome (INS), in certain visual environments. In investigating the effect of stress and motivation on FMNS, a new, if tentative, finding suggests that task-induced stress and/or motivation may have a negative impact on the nystagmus. Taken together, our findings provide an insight into the particular environments and tasks that are likely to present particular challenges to persons with FMNS.