ORCID Profile
0000-0001-6914-5978
Current Organisation
The University of Queensland Queensland Brain Institute
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Cognitive neuroscience | Biological psychology |
Publisher: Center for Open Science
Date: 21-10-2022
Abstract: It is commonly asserted that MRI-derived lesion masks outperform CT-derived lesion masks in lesion-mapping analysis. However, no quantitative analysis has been conducted to support or refute this claim. This study reports an objective comparison of lesion-mapping analyses based on CT- and MRI-derived lesion masks to clarify how input imaging type may ultimately impact analysis results.Routine CT and MRI data were collected from 85 acute stroke survivors. These data were employed to create binarized lesion masks and conduct lesion-mapping analyses on simulated behavioral data. Following standard lesion-mapping analysis methodology, each voxel or region of interest (ROI) were considered as the underlying “target” within CT and MRI data independently. The resulting thresholded z-maps were compared between matched CT- and MRI-based analyses. Paired MRI- and CT-derived lesion masks were found to exhibit good agreement in location, overlap, and size. In single-voxel simulations, MRI-based lesion mapping was able to include more voxels than CT-based analyses, but CT-based analysis results were closer to the underlying target voxel. Simulated lesion symptom mapping results yielded by paired CT and MRI lesion symptom mapping analyses demonstrated good agreement in terms of Dice coefficient when systematic differences in cluster size and lesion overlay are considered. In ROI-level simulations, both CT and MRI-derived analyses yielded low Dice similarity coefficients but no significant differences in performance were identified between modalities.Overall, these results suggest that CT- and MRI-based lesion mapping analyses produce comparable results. This finding is critically important as it suggests that future studies can and should employ CT-derived lesion masks if these scans are available within the appropriate time-window.
Publisher: Center for Open Science
Date: 03-02-2022
Abstract: It is commonly asserted that MRI-derived lesion masks outperform CT-derived lesion masks in lesion-mapping analysis. However, no quantitative analysis has been conducted to support or refute this claim. This study reports an objective comparison of lesion symptom mapping analyses based on CT- and MRI-derived lesion masks to clarify how input imaging type may ultimately impact analysis results.Routine CT and MRI data were collected from 85 acute stroke survivors as part of two cognitive screening studies at Oxford and Leuven. These data were employed to delineate and normalize lesion masks and conduct a series of lesion-symptom mapping analyses on simulated behavioral data. The analyses iteratively considered each impacted voxel as the underlying “target” within CT and MRI data independently. The resulting thresholded z-maps where compared between matched CT- and MRI-based analyses. Paired MRI- and CT-derived lesion masks were found to exhibit good agreement in location, overlap, and size. MRI-based lesion mapping was able to test more voxels than CT-based analyses, but CT-based analysis results were closer to the underlying target voxel. The results yielded by paired CT and MRI lesion symptom mapping analyses demonstrated good agreement in terms of dice coefficient when systematic differences in cluster size and lesion overlay are taken into account. Overall, these results suggest that CT- and MRI-based lesion mapping analyses produce comparable results. This finding is critically important in the context of real-world analyses as it suggests that future studies can and should employ CT-derived lesion masks if these scans are available within the appropriate time-window between infarct and behavioral assessment.
Publisher: Center for Open Science
Date: 25-02-2020
Abstract: ObjectiveHere, we present the Oxford Cognitive Screen-Plus, a computerised tablet-based screen designed to briefly assess domain-general cognition and provide more fine-grained measures of memory and executive function. The OCS-Plus was designed to sensitively screen for cognitive impairments and provide a differentiation between memory and executive deficits. MethodsThe OCS-Plus contains 10 subtasks and requires approximately 24 minutes to complete. In this study, 320 neurologically healthy ageing participants (age M=62.66, SD=13.75) from three sites completed the OCS-Plus. The convergent validity of this assessment was established in comparison to the ACE-R, CERAD and Rey-Osterrieth. Divergent validity was established through comparison with the BDI and tests measuring ergent cognitive-domains. Internal consistency of each subtask was evaluated, and test-retest reliability was determined. ResultsWe established the normative impairment cut-offs for each of the subtasks. Predicted convergent and ergent validity was found, high internal consistency for most measures was also found with the exception of restricted range tasks, as well as strong test-retest reliability, which provided evidence of test stability. Further research demonstrating the use and validity of the OCS-Plus in various clinical populations is required.ConclusionThe OCS-Plus is presented as a standardised cognitive assessment tool, normed and validated in a s le of neurologically healthy participants. The OCS-Plus will be available as an Android App and provides an automated report of domain-general cognitive impairments in executive attention and memory.
Publisher: Elsevier BV
Date: 02-2023
Publisher: Center for Open Science
Date: 29-08-2023
Abstract: Prediction has been shown to play a fundamental role in facilitating efficient perception of simple visual features such as orientation and motion, but it remains unclear whether expectations modulate neural representations of more complex stimuli. Here, we addressed this issue by characterising patterns of brain activity evoked by two-dimensional images of familiar, real-world objects which were either expected or unexpected based on a preceding cue. Participants (n=30) viewed stimuli in rapid serial visual presentation (RSVP) streams which contained both high-fidelity and degraded (diffeomorphically warped) object images. Multivariate pattern analyses of electroencephalography (EEG) data were used to quantify and compare the degree of information represented in neural activity when stimuli were random (unpredictable), expected, or unexpected. Degraded images elicited significantly reduced representational fidelity relative to high-fidelity images. However, degraded images were represented with improved fidelity when they were presented in expected relative to random sequence positions and stimuli in unexpected sequence positions yielded reduced representational fidelity relative to random presentations. Most notably, neural responses to unexpected stimuli contained information pertaining to the expected (but not presented) stimulus. Debriefing at the conclusion of the experiment revealed that participants were not aware of the relationship between cue and target stimuli within the RSVP streams, suggesting that the differences in stimulus decoding between conditions arose in the absence of explicit predictive knowledge. Our findings extend fundamental understanding of how the brain detects and employs predictive relationships to modulate high-level visual perception.
Publisher: Elsevier BV
Date: 03-0007
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2022.108159
Abstract: This large-scale lesion-symptom mapping study investigates the necessary neuro-anatomical substrates of 5 cognitive domains frequently affected post stroke: Language, Attention, Praxis, Number, and Memory. This study aims to demonstrate the validity of using routine clinical brain imaging and standard bedside cognitive screening data from a large, real-world patient cohort for lesion-symptom mapping. Behavioural cognitive screening data from the Oxford Cognitive Screen and routine clinical neuroimaging from 573 acute patients was used in voxel-based lesion-symptom mapping analyses. Patients were classed as impaired or not on each of the subtests within 5 cognitive domains. Distinct patterns of lesion damage were associated with different domains. Language functions were associated with damage to left hemisphere fronto-temporal areas. Visuo-spatial functions were associated with damage to posterior occipital areas (Visual Field) and the right temporo-parietal region (Visual Neglect). Different memory impairments were linked to distinct voxel clusters within the left insular and opercular cortices. Deficits which were not associated with localised voxels (e.g. executive function, praxis) represent distributed, bilateral functions. The standardised, brief Oxford Cognitive Screen was able to reliably differentiate distinct neural correlates critically involved in supporting domain-specific cognitive abilities. By demonstrating and replicating known brain anatomy correlates within real-life clinical cohorts using routinely collected scans and standard bedside screens, we open up VLSM techniques to a wealth of clinically relevant studies which can capitalise on using existing clinical data.
Publisher: Wiley
Date: 30-06-2022
DOI: 10.1111/ENE.15381
Abstract: Unilateral neglect is a common cognitive disorder following stroke. Neglect has a significant impact on functional outcomes, so it is important to detect. However, there is no consensus on which are the best screening tests to administer to detect neglect in time‐limited clinical environments. Members of the European Academy of Neurology Scientific Panel on Higher Cortical Functions, neuropsychologists, occupational therapists, and researchers produced recommendations for primary and secondary tests for bedside neglect testing based on a rigorous literature review, data extraction, online consensus meeting, and subsequent iterations. A total of 512 articles were screened, and 42 were included. These reported data from 3367 stroke survivors assessed using 62 neglect screens. Tests were grouped into cancellation, line bisection, copying, reading/writing, and behavioral. Cancellation tasks were most frequently used (97.6% of studies), followed by bisection, copying, behavioral, and reading/writing assessments. The panel recommended a cancellation test as the primary screening test if there is time to administer only one test. One of several cancellation tests might be used, depending on availability. If time permits, one or more of line bisection, figure copying, and baking tray task were recommended as secondary tests. Finally, if a functional and ecological test is feasible, the Catherine Bergego Scale was recommended. Overall, the literature suggests that no single test on its own is sufficient to exclude a diagnosis of neglect. Therefore, the panel recommended that multiple neglect tests should be used whenever possible. This study provides consensus recommendations for rapid bedside detection of neglect in real‐world, clinical environments.
Publisher: American Psychological Association (APA)
Date: 03-2029
DOI: 10.1037/NEU0000748
Publisher: Cold Spring Harbor Laboratory
Date: 04-04-2021
DOI: 10.1101/2021.03.29.21254555
Abstract: This study aims to investigate how complex visuospatial neglect behavioural phenotypes predict long-term outcomes, both in terms of neglect recovery and broader functional outcomes. This study presents a secondary cohort study of acute and 6 month follow up data from 400 stroke survivors who completed the Oxford Cognitive Screen’s Cancellation Task. At follow-up, patients also completed the Stroke Impact Scale questionnaire. These data were analysed to identify whether any specific combination of neglect symptoms is more likely to result in long-lasting neglect or higher levels of functional impairment, therefore warranting more targeted rehabilitation. Overall, 98/142(69%) neglect cases recovered by follow-up and there was no significant difference in the persistence of egocentric/allocentric (X 2 (1)=0.66, p=0.418 ) or left/right neglect (X 2 (2)=0.781, p= 0.677) . Egocentric neglect was found to follow a proportional recovery pattern with all patients demonstrating a similar level of improvement over time. Conversely, allocentric neglect followed a non-proportional recovery pattern with chronic neglect patients exhibiting a slower rate of improvement than those who recovered. A multiple regression analysis revealed that the initial severity of acute allocentric, but not egocentric, neglect impairment acted as a significant predictor of poor long-term functional outcomes (F(9,383)=3.96, p .001 , R 2 =0.066). Our findings call for systematic neuropsychological assessment of both egocentric and allocentric neglect following stroke, as the occurrence and severity of these conditions may help predict recovery outcomes.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Center for Open Science
Date: 04-03-2022
Abstract: Word-centred neglect dyslexia is most commonly conceptualised as a deficit caused by attentional biases within spatially-coded internal representations of words. However, recent research has suggested that at least some cases of word-centred neglect dyslexia are unrelated to visuospatial neglect and instead involve a deficit of self-inhibition in a phonological route to reading. Here, we set out to provide novel insight into potential underlying mechanisms modulating the occurrence of word-centred lateralised reading errors in healthy participants. A s le of 47 healthy readers completed a novel attentional cueing paradigm in which they sequentially identified lateralised cues and read presented words under limited exposure conditions. Reading responses were analysed to determine whether word-centred neglect dyslexia could be simulated in healthy readers, to compare the strengths of induced biases, and to identify systematic differences in lexical characteristics between target words and neglect dyslexia reading errors. Healthy participants produced frequent lateralised reading errors in both horizontal and vertical reading stimuli with & % of errors classed as neglect dyslexic. Cues appended to word beginnings elicited significantly more reading errors than cues at word ends, illustrating the interaction between existing reading spatial attentional biases and cue-induced biases. Neglect dyslexia reading errors were found to contain significantly more letters per word and had higher concreteness ratings than target words.These findings demonstrate that word-centred neglect dyslexia can be simulated using stimulus-centred attentional cues in healthy readers. This suggests that some cases of word-centred neglect dyslexia may involve a deficit of inference or inhibition rather than a spatial-attentional bias within an internally coded reference frame.
Publisher: Center for Open Science
Date: 04-03-2022
Abstract: Word-centered neglect dyslexia is most commonly characterized as consequence of visuospatial neglect rather than an independent condition. However, recent research has suggested that this deficit may be dissociable from spatial attentional biases. This study aims to evaluate a novel theory of word-centered neglect dyslexia which hypothesizes that this deficit may be related to a self-inhibition impairment rather than visuospatial neglect. Patient EF is a chronic stroke survivor who presented with clear right-lateralized word-centered neglect dyslexia in conjunction with severe left egocentric neglect and left hemianopia following a right PCA stroke. The severity of EF’s neglect dyslexia was not found to be affected by factors which modulate the severity of visuospatial neglect. EF demonstrated an intact ability to identify all letters in words, but reliably committed neglect dyslexia errors when subsequently reading the same words as a whole. EF did not exhibit neglect dyslexic impairment in standardized spelling, word-meaning matching, and word-picture matching tasks. Critically, EF exhibited marked self-inhibition impairment and committed neglect dyslexia errors which were characterized by misreading less familiar target words as more familiar responses. This behavioural pattern cannot be clearly accounted for by theories which characterize word-centered neglect dyslexia as a consequence of neglect. Instead, this data suggests that at least some cases of word-centered neglect dyslexia may be better understood as inhibitional deficits. Overall, these novel findings call for revision to the dominant model of word-centered neglect dyslexia.
Publisher: Center for Open Science
Date: 21-10-2022
Abstract: While visuospatial neglect is commonly associated with damage to the right posterior parietal cortex, neglect is an anatomically heterogenous syndrome. This project presents a systematic review of 34 lesion-mapping studies reporting on the anatomical correlates of neglect. Specifically, the reported correlates of egocentric versus allocentric, acute versus chronic, personal versus extra-personal, and left versus right hemisphere neglect are summarised. The quality of each included lesion-mapping analysis was then evaluated to identify methodological factors which may help account for the reported variance in correlates of neglect.Overall, the existing literature strongly suggests that egocentric and allocentric neglect represent anatomically dissociable conditions and that the anatomy of these conditions may not be entirely homologous across hemispheres. Studies which have compared the anatomy of acute versus chronic neglect have found that these conditions are associated with distinct lesion loci, while studies comparing the correlates of peripersonal/extrapersonal neglect are split as to whether these neglect subtypes are anatomically dissociable. The included studies employed a wide range of lesion-mapping analysis techniques, each producing results of varying quality and generalisability. This review concludes that the reported underlying anatomical correlates of heterogeneous visuospatial neglect vary considerably. Future, high quality studies are needed to investigate patterns of disconnection associated with clearly defined forms of visuospatial neglect in large and representative s les.
Publisher: Springer Science and Business Media LLC
Date: 06-07-2023
DOI: 10.3758/S13414-023-02753-X
Abstract: Word-centred neglect dyslexia is most commonly conceptualised as a deficit caused by attentional biases within spatially coded internal representations of words. However, recent research has suggested that at least some cases of word-centred neglect dyslexia are unrelated to visuospatial neglect and may instead be modulated by self-inhibition and lexical factors. Here, we set out to provide novel insight into potential underlying mechanisms modulating the occurrence of word-centred lateralised reading errors in healthy participants. A s le of 47 healthy readers completed a novel attentional cueing paradigm in which they sequentially identified lateral cues and read presented words under limited exposure conditions. Reading responses were analysed to determine whether word-centred neglect dyslexia could be simulated in healthy readers, to compare the strengths of induced biases, and to identify systematic differences in lexical characteristics between target words and neglect dyslexia reading errors. Healthy participants produced frequent lateralised reading errors in both horizontal and vertical reading stimuli with 50% of errors classed as neglect dyslexic. Cues appended to word beginnings elicited significantly more reading errors than cues at word ends, illustrating the interaction between existing reading spatial attentional biases and cue-induced biases. Neglect dyslexia reading errors were found to contain significantly more letters per word and had higher concreteness ratings than target words. These findings demonstrate that word-centred neglect dyslexia can be simulated using attentional cues in healthy readers. These results provide important insight into the mechanisms underlying word-centred neglect dyslexia and further fundamental understanding of this syndrome.
Publisher: Cold Spring Harbor Laboratory
Date: 19-02-2021
DOI: 10.1101/2021.02.17.21251846
Abstract: This large-scale lesion-symptom mapping study aimed to investigate the necessary neuro-anatomical substrates of 5 cognitive domains frequently affected post stroke: Language, Attention, Praxis, Number, and Memory. This study aims to demonstrate the validity of using routine clinical brain imaging from a large, real-world patient cohort for lesion-symptom mapping. Behavioural cognitive screening data from the Oxford Cognitive Screen and routine clinical neuroimaging from 573 acute patients was used in voxel-based lesion-symptom mapping analyses. Patients were classed as impaired or not on each of the subtests within 5 cognitive domains. Distinct patterns of lesion damage were associated with different domains. Language functions were associated with damage to left hemisphere fronto-temporal areas. Visuo-spatial functions were associated with damage to posterior occipital areas (Visual Field) and the right temporo-parietal region (Visual Neglect). Different memory impairments were linked to distinct voxel clusters within the left insular and opercular cortices. Deficits which were not associated with localised voxels (e.g. praxis, executive function) represent distributed functions. The standardised, brief Oxford Cognitive Screen was able to reliably differentiate distinct neural correlates critically involved in supporting domain-specific cognitive abilities. By demonstrating and replicating known brain anatomy correlates within real-life clinical cohorts using routine CT scans, we open up VLSM techniques to a wealth of clinically relevant studies which can capitalise on using existing clinical brain imaging.
Publisher: Elsevier BV
Date: 06-2023
Publisher: Center for Open Science
Date: 07-02-2022
Abstract: Background and purpose: Unilateral neglect is a common cognitive disorder following stroke. Neglect has a significant impact on functional outcomes, so it is important to detect. However, there is no consensus on which are the best screening tests to administer to detect neglect in time-limited clinical environments.Methods: Members of the European Academy of Neurology Scientific Panel on Higher Cortical Functions, neuropsychologists, occupational therapists, and researchers produced recommendations for primary and secondary tests for bedside neglect testing based on a rigorous literature review, data extraction, online consensus meeting, and subsequent iterations.Results: 512 articles were screened with 42 included. These reported data from 3367 stroke survivors assessed using 62 neglect screens. Tests were grouped into cancellation, line bisection, copy, reading/writing, and behavioural. Cancellation tasks were most frequently used (97.6% of studies) followed by bisection, copy, behavioural, and reading/writing assessments. The panel recommended a cancellation test as the primary screening test if there is time to administer only one test. One of several cancellation tests might be used, depending on availability. If time permits, one or more of line bisection, figure copying and baking tray task were recommended as secondary tests. Finally, if a functional and ecological test is feasible, the Catherine Bergego Scale was recommended. Overall, literature suggests that no single test on its own is sufficient to exclude a diagnosis of neglect. Therefore, the panel recommended that multiple neglect tests should be used whenever possible.Conclusions: This study provides consensus recommendations for rapid bedside detection of neglect in real-world, clinical environments.
Publisher: Elsevier BV
Date: 06-2023
Publisher: Springer Science and Business Media LLC
Date: 11-09-2023
Publisher: Center for Open Science
Date: 21-10-2022
Abstract: Visuospatial neglect, a common lateralised disorder of perception following acute stroke, is widely considered a disconnection syndrome, though the patterns of dysconnectivity associated with neglect remain unclear. Here we had 530 acute stroke survivors (age = 72.8, 44.3% female) undertake standardised neglect testing and routine clinical imaging. The data were used to conduct voxel-wise, tract-level, and network-level lesion-mapping analyses aimed at localising the neural correlates of left and right egocentric (body-centred) and allocentric (object-centred) neglect. Only minimal anatomical homogeneity was present between the correlates of right and left egocentric neglect across all analysis types. This finding challenges previous work suggesting that right and left neglect are anatomically homologous, and instead suggests that egocentric neglect may involve damage to a shared, but hemispherically asymmetric attention network. By contrast, egocentric and allocentric neglect were associated with dysconnectivity in a distinct but overlapping set of network edges, with both deficits related to damage across the dorsal and ventral attention networks. Critically, this finding suggests that the distinction between egocentric and allocentric neglect is unlikely to reflect a simple dichotomy between dorsal versus ventral networks dysfunction, as is commonly asserted. Taken together, the current findings provide a fresh perspective on the neural circuitry involved in regulating visuospatial attention, and provide important clues to understanding the cognitive and perceptual processes involved in this common and debilitating neuropsychological syndrome.
Publisher: Cold Spring Harbor Laboratory
Date: 20-06-2023
DOI: 10.1101/2023.06.14.23291381
Abstract: Cognitive screening following stroke is widely recommended, yet few studies have investigated the prognostic value of acute domain-specific function for longer-term cognitive outcome. This study aimed to determine the prevalence of domain-specific impairment acutely and at 6 months, assess the proportion of change in cognitive performance, and examine the predictive value of acute domain-specific cognitive screening. A prospective cohort of consecutive stroke survivors completed the Oxford Cognitive Screen acutely (≤2 weeks) and 6 months post-stroke. Hierarchical multivariable regression analyses were used to predict general and domain-specific cognitive impairment at 6 months. Demographic/clinical covariates included age, sex, education, atrial fibrillation, hypertension, diabetes, smoking, stroke severity, lesion volume, recurrent stroke, and days to cognitive assessment. A total of 430 stroke survivors (mean age 73.9 years (12.5 SD ), 46.5% female, median NIHSS 5 [IQR 2-10]) completed 6-month follow-up. Impairments were prevalent within all domains at both timepoints, ranging from 26.7% (n=112) in praxis to 46.8% (n=183) in attention acutely, and 19.6% (n=79) in praxis to 32.6% (n=140) in language at 6 months. Proportion of recovery was highest in praxis (n=73, 71%) and lowest in language (n=89, 46%) and memory (n=82, 48%). Severity of 6-month cognitive impairment was best predicted by the addition of proportion of acute subtests impaired (adjusted R 2 =0.298, p .0001) over demographic/clinical factors alone (adjusted R 2 =0.105, p .0001). Acute cognitive function (β=0.403 SE 0.042, p .0001) was the strongest predictor of 6-month cognitive performance. Acute domain-specific impairments in memory (β=0.116 SE 0.027, p .0001), language (β=0.095 SE 0.027, p .0001) and praxis (β=0.086 SE 0.028, p .0001) were significant predictors of severity of cognitive impairment at follow-up. Cognitive impairment is highly prevalent initially after stroke across all domains, though impairments in language, memory and attention predominate at 6 months. Early domain-specific screening provides valuable prognostic information with respect to longer-term cognitive functioning. Several demographic, stroke-related, vascular, and brain-related risk factors for post-stroke cognitive impairment have been identified, however, there is a lack of established early domain-specific cognitive markers of long-term cognitive outcome despite an emphasis on routine post-stroke cognitive screening. This study showed that severity of acute cognitive impairment identified through early domain-specific screening with the Oxford Cognitive Screen (OCS) was the strongest predictor of cognitive function at follow-up when compared to common post-stroke cognitive risk factors alone. Impairments in memory, language and praxis domains acutely after stroke were particularly important in predicting the severity of cognitive impairment at 6 months. This study demonstrated for the first time that early domain-specific screening after stroke with the OCS provides valuable prognostic information with respect to long-term cognitive functioning. Each post-stroke cognitive profile is unique and therefore highlighting different strengths and weaknesses in performance early allows for more accurate information to be communicated to the patient, more tailored discharge care packages and appropriate allocation of rehabilitation resources.
Publisher: Cold Spring Harbor Laboratory
Date: 04-04-2021
DOI: 10.1101/2021.03.29.21254222
Abstract: Multiverse analysis provides an ideal tool for understanding how inherent, yet ultimately arbitrary methodological choices impact the conclusions of in idual studies. With this investigation we aimed to demonstrate the utility of multiverse analysis for evaluating generalisability and identifying potential sources of bias within studies employing neurological populations. Multiverse analysis was used to evaluate the robustness of the relationship between post-stroke visuospatial neglect and poor long term recovery outcome within a s le of 1113 (age =72.5, 45.1% female) stroke survivors. A total of 25,600 t-test comparisons were run across 400 different patient groups defined using various combinations of valid inclusion criteria based on lesion location, stroke type, assessment time, neglect impairment definition, and scoring criteria across 16 standardised outcome measures. Overall, 33.9% of conducted comparisons yielded significant results. 99.9% of these significant results fell below the null specification curve, indicating a highly robust relationship between neglect and poor recovery outcome. However, the strength of this effect was not constant across all comparison groups. Comparisons which included participants, pre-selected patients based on lesion type, or failed to account for allocentric neglect impairment were found to yield average effect sizes which differed substantially. Similarly, average effect sizes differed across various outcome measures with the strongest average effect in comparisons involving an activities of daily living measure and the weakest in comparisons employing a depression subscale. This investigation demonstrates the utility of multiverse analysis techniques for evaluating effect robustness and identifying potential sources of bias within neurological research.
Publisher: SAGE Publications
Date: 16-07-2021
DOI: 10.1177/15459683211032977
Abstract: Background/Objective. This study aims to investigate how complex visuospatial neglect behavioural phenotypes predict long-term outcomes, both in terms of neglect recovery and broader functional outcomes after 6 months post-stroke. Methods. This study presents a secondary cohort study of acute and 6-month follow-up data from 400 stroke survivors who completed the Oxford Cognitive Screen’s Cancellation Task. At follow-up, patients also completed the Stroke Impact Scale questionnaire. These data were analysed to identify whether any specific combination of neglect symptoms is more likely to result in long-lasting neglect or higher levels of functional impairment, therefore warranting more targeted rehabilitation. Results. Overall, 98/142 (69%) neglect cases recovered by follow-up, and there was no significant difference in the persistence of egocentric/allocentric (X 2 [1] = .66 and P = .418) or left/right neglect (X 2 [2] = .781 and P = .677). Egocentric neglect was found to follow a proportional recovery pattern with all patients demonstrating a similar level of improvement over time. Conversely, allocentric neglect followed a non-proportional recovery pattern with chronic neglect patients exhibiting a slower rate of improvement than those who recovered. A multiple regression analysis revealed that the initial severity of acute allocentric, but not egocentric, neglect impairment acted as a significant predictor of poor long-term functional outcomes (F [9,300] = 4.742, P .001 and adjusted R 2 = .098). Conclusions. Our findings call for systematic neuropsychological assessment of both egocentric and allocentric neglect following stroke, as the occurrence and severity of these conditions may help predict recovery outcomes over and above stroke severity alone.
Publisher: Center for Open Science
Date: 28-02-2023
Abstract: Although many executive function screens have been developed, it is not yet clear whether these assessments are equally effective in detecting post-stroke deficits of initiation and inhibition. This study presents a comparative analysis of the Stroop and Hayling Tests aiming to evaluate whether these tests measure the same underlying cognitive functions and to identify the neural correlates of the deficits detected by both tasks. 66 stroke survivors and 70 healthy ageing controls completed the Hayling and Stroop Tasks. Stroke patients were found to exhibit qualitative performance differences across analogous Stroop and Hayling Test metrics intended to tap initiation and inhibition. The Stroop Test was found to have high specificity to abnormal performance, but low sensitivity relative to the Hayling Task. Minimal overlap was present between the network-level correlates of analogous Stroop and Hayling Test metrics. Hayling Task strategy use metrics were significantly associated with distinct patterns of disconnection in stroke survivors, providing novel insight into the neural correlates of fine-grained behavioural patterns. Overall, these findings strongly suggest that the functions tapped by the Stroop and Hayling Test are both behaviourally and anatomically dissociable. The Hayling Task was found to offer improved sensitivity and detail relative to the Stroop Task. This novel demonstration of the Hayling Test within the stroke population suggests that this task represents an effective measure for quantifying post-stroke initiation and inhibition deficits.
Publisher: Center for Open Science
Date: 18-11-2020
Abstract: ObjectiveComplex Figure Copy Tasks are one of the most commonly employed neuropsychological tests. However, manual scoring of this test is time-consuming, requires training, and can then still be inconsistent between different examiners. We aimed to develop and evaluate a novel, automated method for scoring a tablet-based Figure Copy Task. MethodA cohort of 261 healthy adults and 203 stroke survivors completed the computerised Oxford Cognitive Screen – Plus Figure Copy Task. Responses were independently scored by two trained human raters and by a novel automated scoring program. ResultsOverall, the Automated Scoring Program was able to reliably extract and identify the separate figure elements (average sensitivity and specificity of 92.10% and 90.20% respectively) and assigned total scores which agreed well with manual scores (ICC = .83). Receiver Operating Curve analysis demonstrated that, compared to overall impairment categorisations based on manual scores, the Automated Scoring Program had an overall sensitivity and specificity of 80% and 93.40% respectively (AUC = 86.70%). Automated total scores also reliably distinguished between different clinical impairment groups with acute stroke survivors scoring significantly worse than longer term survivors, which in turn scored worse than neurologically healthy adults. ConclusionsThese results demonstrate that the novel automated scoring algorithm was able to reliably extract and accurately score Figure Copy Task data, even in cases where drawings were highly distorted due to comorbid fine-motor deficits. This represents a significant advancement as this novel technology can be employed to produce immediate, unbiased, and reproducible scores for Figure Copy Task responses in clinical and research environments.
Publisher: Center for Open Science
Date: 30-03-2021
Abstract: Visuospatial neglect is a heterogenous syndrome which can occur following damage to either right or left hemisphere areas. This study employs voxel-lesion symptom mapping to identify the neural correlates of left and right egocentric and allocentric neglect in a large acute stroke cohort.A cohort of 446 acute stroke survivors (age = 26-95, 44% female) completed neuropsychological neglect assessment and routine clinical imaging. Similar to previous investigations, left egocentric and left allocentric neglect were associated with damage to distinct clusters of voxels within the posterior parietal and temporo-parietal junction areas. Unlike previous investigations, right egocentric neglect was found to most strongly associated with damage to more posterior voxels within left occipital cortical areas. Right allocentric neglect was found to be most strongly associated with damage to the anterior limb of the left internal capsule. Interestingly, the right hemisphere homologues of the areas implicated in right-lateralised neglect were not overlapping with those associated with left neglect impairment. This dissociation was present across both egocentric and allocentric neglect impairment. The results of this investigation suggest that right egocentric/allocentric neglect should not be characterised as a consequence of damage to left-hemisphere homologues of the right hemisphere attentional systems. These findings support the characterisation of visuospatial neglect as a heterogenous cluster of impairments rather than a unitary syndrome and provide novel insight into the neural correlates of spatial attention.
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.CORTEX.2018.10.024
Abstract: Neglect Dyslexia is a neuropsychological syndrome in which patients commit consistently lateralised letter omission, addition, and substitution errors when reading in idual words. Although neglect dyslexia frequently co-occurs with domain-general visuospatial neglect, some cases of neglect dyslexia may be best characterised as a dissociable impairment within a word-centred reference frame. This investigation employs data from a single case study of a patient who demonstrated word-centred neglect dyslexia to clarify neglect dyslexia's relationship with visuospatial neglect. AB completed the Oxford Cognitive Screen and an original reading assessment in which she read 302 words, pseudo-words, and numbers presented in normal, vertical, and mirror-reflected orientations. AB was found to commit consistently lateralised right neglect dyslexia errors (e.g., SHOWN misread as "show" or RELATED misread as "relate"). By contrast, AB did not exhibit object-centred or viewer-centred neglect. AB was also found to commit lateralised reading errors affecting the terminal portions of words when lateralised spatial bias was eliminated by presenting words vertically. Additionally, AB consistently misread terminal letters (originally right-lateralised) even when words were mirror-reflected so that these letters were presented in the left side of space. AB committed no neglect dyslexia errors when reading normally, vertically, or mirror-reflected numbers, and demonstrated a qualitatively different error pattern when reading pseudo-words. The results of this case study imply that neglect dyslexia can involve a content-specific, word-centred cognitive deficit and can be dissociated from egocentric and allocentric visuospatial neglect.
Publisher: Springer Science and Business Media LLC
Date: 29-05-2021
DOI: 10.1007/S00415-021-10612-8
Abstract: Multiverse analysis provides an ideal tool for understanding how inherent, yet ultimately arbitrary methodological choices impact the conclusions of in idual studies. With this investigation, we aimed to demonstrate the utility of multiverse analysis for evaluating generalisability and identifying potential sources of bias within studies employing neurological populations. Multiverse analysis was used to evaluate the robustness of the relationship between post-stroke visuospatial neglect and poor long-term recovery outcome within a s le of 1113 (age = 72.5, 45.1% female) stroke survivors. A total of 25,600 t -test comparisons were run across 400 different patient groups defined using various combinations of valid inclusion criteria based on lesion location, stroke type, assessment time, neglect impairment definition, and scoring criteria across 16 standardised outcome measures. Overall, 33.9% of conducted comparisons yielded significant results. 99.9% of these significant results fell below the null specification curve, indicating a highly robust relationship between neglect and poor recovery outcome. However, the strength of this effect was not constant across all comparison groups. Comparisons which included 100 participants, pre-selected patients based on lesion type, or failed to account for allocentric neglect impairment were found to yield average effect sizes which differed substantially. Similarly, average effect sizes differed across various outcome measures with the strongest average effect in comparisons involving an activities of daily living measure and the weakest in comparisons employing a depression subscale. This investigation demonstrates the utility of multiverse analysis techniques for evaluating effect robustness and identifying potential sources of bias within neurological research.
Publisher: BMJ
Date: 23-01-2019
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2024
End Date: 12-2026
Amount: $440,970.00
Funder: Australian Research Council
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