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Dennis Velakoulis - One of the best experts on this subject based on the ideXlab platform.
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Saccadic Eye Movement Characteristics in Adult Niemann-Pick Type C Disease: Relationships with Disease Severity and Brain Structural Measures
2016Co-Authors: Larry A. Abel, Michael C Fahey, Elizabeth A. Bowman, Dennis Velakoulis, Patricia Desmond, Matthew D. Macfarlane, Jeffrey Chee, Leong Looi, Christopher L. Adamson, Mark WalterfangAbstract:Niemann-Pick Type C disease (NPC) is a rare genetic disorder of lipid metabolism. A parameter related to horizontal Saccadic peak Velocity was one of the primary outcome measures in the clinical trial assessing miglustat as a treatment for NPC. Neuropathology is widespread in NPC, however, and could be expected to affect other Saccadic parameters. We compared horizontal Saccadic Velocity, latency, gain, antisaccade error percentage and self-paced saccade generation in 9 adult NPC patients to data from 10 age-matched controls. These Saccadic measures were correlated with appropriate MRI-derived brain structural measures (e.g., dorsolateral prefrontal cortex, frontal eye fields, supplemental eye fields, parietal eye fields, pons, midbrain and cerebellar vermis) and with measures of disease severity and duration. The best discriminators between groups were reflexive saccade gain and the two volitional saccade measures. Gain was also the strongest correlate with disease severity and duration. Most of the Saccadic measures showed strongly significant correlations with neurophysiologically appropriate brain regions. While our patient sample is small, the apparent specificity of these relationships suggests that as new diagnostic methods and treatments become available for NPC, a broader range o
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longitudinal assessment of reflexive and volitional saccades in niemann pick type c disease during treatment with miglustat
Orphanet Journal of Rare Diseases, 2015Co-Authors: Larry A. Abel, Dennis Velakoulis, Mark Walterfang, Elizabeth Bowman, Matthew J StainerAbstract: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. 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. 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. 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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Saccadic eye movement characteristics in adult niemann pick type c disease relationships with disease severity and brain structural measures
PLOS ONE, 2012Co-Authors: Larry A. Abel, Michael C Fahey, Dennis Velakoulis, Patricia Desmond, Matthew D. Macfarlane, Elizabeth Bowman, Jeffrey C L LooiAbstract:Niemann-Pick Type C disease (NPC) is a rare genetic disorder of lipid metabolism. A parameter related to horizontal Saccadic peak Velocity was one of the primary outcome measures in the clinical trial assessing miglustat as a treatment for NPC. Neuropathology is widespread in NPC, however, and could be expected to affect other Saccadic parameters. We compared horizontal Saccadic Velocity, latency, gain, antisaccade error percentage and self-paced saccade generation in 9 adult NPC patients to data from 10 age-matched controls. These Saccadic measures were correlated with appropriate MRI-derived brain structural measures (e.g., dorsolateral prefrontal cortex, frontal eye fields, supplemental eye fields, parietal eye fields, pons, midbrain and cerebellar vermis) and with measures of disease severity and duration. The best discriminators between groups were reflexive saccade gain and the two volitional saccade measures. Gain was also the strongest correlate with disease severity and duration. Most of the Saccadic measures showed strongly significant correlations with neurophysiologically appropriate brain regions. While our patient sample is small, the apparent specificity of these relationships suggests that as new diagnostic methods and treatments become available for NPC, a broader range of Saccadic measures may be useful tools for the assessment of disease progression and treatment efficacy.
Michael C Fahey - One of the best experts on this subject based on the ideXlab platform.
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Saccadic Eye Movement Characteristics in Adult Niemann-Pick Type C Disease: Relationships with Disease Severity and Brain Structural Measures
2016Co-Authors: Larry A. Abel, Michael C Fahey, Elizabeth A. Bowman, Dennis Velakoulis, Patricia Desmond, Matthew D. Macfarlane, Jeffrey Chee, Leong Looi, Christopher L. Adamson, Mark WalterfangAbstract:Niemann-Pick Type C disease (NPC) is a rare genetic disorder of lipid metabolism. A parameter related to horizontal Saccadic peak Velocity was one of the primary outcome measures in the clinical trial assessing miglustat as a treatment for NPC. Neuropathology is widespread in NPC, however, and could be expected to affect other Saccadic parameters. We compared horizontal Saccadic Velocity, latency, gain, antisaccade error percentage and self-paced saccade generation in 9 adult NPC patients to data from 10 age-matched controls. These Saccadic measures were correlated with appropriate MRI-derived brain structural measures (e.g., dorsolateral prefrontal cortex, frontal eye fields, supplemental eye fields, parietal eye fields, pons, midbrain and cerebellar vermis) and with measures of disease severity and duration. The best discriminators between groups were reflexive saccade gain and the two volitional saccade measures. Gain was also the strongest correlate with disease severity and duration. Most of the Saccadic measures showed strongly significant correlations with neurophysiologically appropriate brain regions. While our patient sample is small, the apparent specificity of these relationships suggests that as new diagnostic methods and treatments become available for NPC, a broader range o
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Saccadic eye movement characteristics in adult niemann pick type c disease relationships with disease severity and brain structural measures
PLOS ONE, 2012Co-Authors: Larry A. Abel, Michael C Fahey, Dennis Velakoulis, Patricia Desmond, Matthew D. Macfarlane, Elizabeth Bowman, Jeffrey C L LooiAbstract:Niemann-Pick Type C disease (NPC) is a rare genetic disorder of lipid metabolism. A parameter related to horizontal Saccadic peak Velocity was one of the primary outcome measures in the clinical trial assessing miglustat as a treatment for NPC. Neuropathology is widespread in NPC, however, and could be expected to affect other Saccadic parameters. We compared horizontal Saccadic Velocity, latency, gain, antisaccade error percentage and self-paced saccade generation in 9 adult NPC patients to data from 10 age-matched controls. These Saccadic measures were correlated with appropriate MRI-derived brain structural measures (e.g., dorsolateral prefrontal cortex, frontal eye fields, supplemental eye fields, parietal eye fields, pons, midbrain and cerebellar vermis) and with measures of disease severity and duration. The best discriminators between groups were reflexive saccade gain and the two volitional saccade measures. Gain was also the strongest correlate with disease severity and duration. Most of the Saccadic measures showed strongly significant correlations with neurophysiologically appropriate brain regions. While our patient sample is small, the apparent specificity of these relationships suggests that as new diagnostic methods and treatments become available for NPC, a broader range of Saccadic measures may be useful tools for the assessment of disease progression and treatment efficacy.
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vestibular Saccadic and fixation abnormalities in genetically confirmed friedreich ataxia
Brain, 2008Co-Authors: Michael C Fahey, Louise A. Corben, Phillip D Cremer, Lynette Millist, M J Todd, Owen White, Michael Halmagyi, Veronica Collins, Andrew J Churchyard, Kim TanAbstract:Friedreich ataxia (FRDA), the commonest of the inherited ataxias, is a multisystem neurodegenerative condition that affects ocular motor function. We assessed eye movement abnormalities in 20 individuals with genetically confirmed FRDA and compared these results to clinical measures. All subjects were assessed with infrared oculography. Fifteen individuals underwent a full protocol of eye movement recordings. Ten subjects were analysed using two-dimensional scleral coil equipment and five using three-dimensional scleral coil recording equipment. We also recorded visual quality of life, Sloan low contrast letter acuity and Friedreich Ataxia Rating Scale scores to compare to the visual measures. Whilst Saccadic Velocity was essentially normal, Saccadic latency was prolonged. The latency correlated with clinical measures of disease severity, including the scores for the Friedreich Ataxia Rating Scale and the Sloan low contrast letter acuity tests. Fixation abnormalities consisting of square wave jerks and ocular flutter were common, and included rare examples of vertical square wave jerks. Vestibular abnormalities were also evident in the group, with markedly reduced vestibulo-ocular reflex gain and prolonged latency. The range of eye movement abnormalities suggest that neurological dysfunction in FRDA includes brainstem, cortical and vestibular pathways. Severe vestibulopathy with essentially normal Saccadic Velocity are hallmarks of FRDA and differentiate it from a number of the dominant spinocerebellar ataxias. The correlation of Saccadic latency with FARS score raises the possibility of its use as a biomarker for FRDA clinical trials.
Kim Tan - One of the best experts on this subject based on the ideXlab platform.
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vestibular Saccadic and fixation abnormalities in genetically confirmed friedreich ataxia
Brain, 2008Co-Authors: Michael C Fahey, Louise A. Corben, Phillip D Cremer, Lynette Millist, M J Todd, Owen White, Michael Halmagyi, Veronica Collins, Andrew J Churchyard, Kim TanAbstract:Friedreich ataxia (FRDA), the commonest of the inherited ataxias, is a multisystem neurodegenerative condition that affects ocular motor function. We assessed eye movement abnormalities in 20 individuals with genetically confirmed FRDA and compared these results to clinical measures. All subjects were assessed with infrared oculography. Fifteen individuals underwent a full protocol of eye movement recordings. Ten subjects were analysed using two-dimensional scleral coil equipment and five using three-dimensional scleral coil recording equipment. We also recorded visual quality of life, Sloan low contrast letter acuity and Friedreich Ataxia Rating Scale scores to compare to the visual measures. Whilst Saccadic Velocity was essentially normal, Saccadic latency was prolonged. The latency correlated with clinical measures of disease severity, including the scores for the Friedreich Ataxia Rating Scale and the Sloan low contrast letter acuity tests. Fixation abnormalities consisting of square wave jerks and ocular flutter were common, and included rare examples of vertical square wave jerks. Vestibular abnormalities were also evident in the group, with markedly reduced vestibulo-ocular reflex gain and prolonged latency. The range of eye movement abnormalities suggest that neurological dysfunction in FRDA includes brainstem, cortical and vestibular pathways. Severe vestibulopathy with essentially normal Saccadic Velocity are hallmarks of FRDA and differentiate it from a number of the dominant spinocerebellar ataxias. The correlation of Saccadic latency with FARS score raises the possibility of its use as a biomarker for FRDA clinical trials.
Leandro L Di Stasi - One of the best experts on this subject based on the ideXlab platform.
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monitoring driver fatigue using a single channel electroencephalographic device a validation study by gaze based driving performance and subjective data
Accident Analysis & Prevention, 2017Co-Authors: Jose M Morales, Carolina Diazpiedra, Hector Rieiro, Joaquin Rocagonzalez, Samuel Romero, Andres Catena, Luis J Fuentes, Leandro L Di StasiAbstract:Abstract Driver fatigue can impair performance as much as alcohol does. It is the most important road safety concern, causing thousands of accidents and fatalities every year. Thanks to technological developments, wearable, single-channel EEG devices are now getting considerable attention as fatigue monitors, as they could help drivers to assess their own levels of fatigue and, therefore, prevent the deterioration of performance. However, the few studies that have used single-channel EEG devices to investigate the physiological effects of driver fatigue have had inconsistent results, and the question of whether we can monitor driver fatigue reliably with these EEG devices remains open. Here, we assessed the validity of a single-channel EEG device (TGAM-based chip) to monitor changes in mental state (from alertness to fatigue). Fifteen drivers performed a 2-h simulated driving task while we recorded, simultaneously, their prefrontal brain activity and Saccadic Velocity. We used Saccadic Velocity as the reference index of fatigue. We also collected subjective ratings of alertness and fatigue, as well as driving performance. We found that the power spectra of the delta EEG band showed an inverted U-shaped quadratic trend (EEG power spectra increased for the first hour and half, and decreased during the last thirty minutes), while the power spectra of the beta band linearly increased as the driving session progressed. Coherently, Saccadic Velocity linearly decreased and speeding time increased, suggesting a clear effect of fatigue. Subjective data corroborated these conclusions. Overall, our results suggest that the TGAM-based chip EEG device is able to detect changes in mental state while performing a complex and dynamic everyday task as driving.
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effects of long and short simulated flights on the Saccadic eye movement Velocity of aviators
Physiology & Behavior, 2016Co-Authors: Andres Catena, Leandro L Di Stasi, Michael B Mccamy, Susana Martinezconde, Ellis C Gayles, Chad Hoare, Michael Foster, Stephen L MacknikAbstract:Aircrew fatigue is a major contributor to operational errors in civil and military aviation. Objective detection of pilot fatigue is thus critical to prevent aviation catastrophes. Previous work has linked fatigue to changes in oculomotor dynamics, but few studies have studied this relationship in critical safety environments. Here we measured the eye movements of US Marine Corps combat helicopter pilots before and after simulated flight missions of different durations.We found a decrease in Saccadic velocities after long simulated flights compared to short simulated flights. These results suggest that Saccadic Velocity could serve as a biomarker of aviator fatigue.
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risk behaviour and mental workload multimodal assessment techniques applied to motorbike riding simulation
Transportation Research Part F-traffic Psychology and Behaviour, 2009Co-Authors: Leandro L Di Stasi, Andres Catena, Vanessa Alvarezvalbuena, Jose J Canas, Antonio Maldonado, Adoracion Antoli, Antonio CandidoAbstract:We present data from an ongoing research project on the cognitive, emotional and neuropsychological basis of risk behaviour. The main aim of the project is to build a model of risk behaviour so that if we know certain cognitive, behavioural and emotional variables, we will be able to predict decisions made in the face of uncertainty and risk, with the final goal of designing programs for evaluating, preventing and controlling risk behaviour. The objective of the present study was to look for individual differences in hazard perception during a static riding simulation and their relationship with mental workload. We used a multidimensional methodology, including behavioural, subjective and physiological data. The behavioural measures were obtained in a static riding simulation during eight hazard situations. We evaluated whether eye activity measures correlated with cognitive workload and different types of risky behaviours. Eye movement parameters were measured using a video-based eye tracking system. We found that risk-prone individuals showed specific patterns of risky behaviours and that peak of Saccadic Velocity and subjective mental workload indexes were both reliable indicators of risk proneness. Mental workload was higher for participants showing attitudes to risk behaviours probably because of a lack of conscious awareness of specific cues indicating dangerous scenarios.
Larry A. Abel - One of the best experts on this subject based on the ideXlab platform.
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Saccadic Eye Movement Characteristics in Adult Niemann-Pick Type C Disease: Relationships with Disease Severity and Brain Structural Measures
2016Co-Authors: Larry A. Abel, Michael C Fahey, Elizabeth A. Bowman, Dennis Velakoulis, Patricia Desmond, Matthew D. Macfarlane, Jeffrey Chee, Leong Looi, Christopher L. Adamson, Mark WalterfangAbstract:Niemann-Pick Type C disease (NPC) is a rare genetic disorder of lipid metabolism. A parameter related to horizontal Saccadic peak Velocity was one of the primary outcome measures in the clinical trial assessing miglustat as a treatment for NPC. Neuropathology is widespread in NPC, however, and could be expected to affect other Saccadic parameters. We compared horizontal Saccadic Velocity, latency, gain, antisaccade error percentage and self-paced saccade generation in 9 adult NPC patients to data from 10 age-matched controls. These Saccadic measures were correlated with appropriate MRI-derived brain structural measures (e.g., dorsolateral prefrontal cortex, frontal eye fields, supplemental eye fields, parietal eye fields, pons, midbrain and cerebellar vermis) and with measures of disease severity and duration. The best discriminators between groups were reflexive saccade gain and the two volitional saccade measures. Gain was also the strongest correlate with disease severity and duration. Most of the Saccadic measures showed strongly significant correlations with neurophysiologically appropriate brain regions. While our patient sample is small, the apparent specificity of these relationships suggests that as new diagnostic methods and treatments become available for NPC, a broader range o
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longitudinal assessment of reflexive and volitional saccades in niemann pick type c disease during treatment with miglustat
Orphanet Journal of Rare Diseases, 2015Co-Authors: Larry A. Abel, Dennis Velakoulis, Mark Walterfang, Elizabeth Bowman, Matthew J StainerAbstract: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. 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. 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. 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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Saccadic eye movement characteristics in adult niemann pick type c disease relationships with disease severity and brain structural measures
PLOS ONE, 2012Co-Authors: Larry A. Abel, Michael C Fahey, Dennis Velakoulis, Patricia Desmond, Matthew D. Macfarlane, Elizabeth Bowman, Jeffrey C L LooiAbstract:Niemann-Pick Type C disease (NPC) is a rare genetic disorder of lipid metabolism. A parameter related to horizontal Saccadic peak Velocity was one of the primary outcome measures in the clinical trial assessing miglustat as a treatment for NPC. Neuropathology is widespread in NPC, however, and could be expected to affect other Saccadic parameters. We compared horizontal Saccadic Velocity, latency, gain, antisaccade error percentage and self-paced saccade generation in 9 adult NPC patients to data from 10 age-matched controls. These Saccadic measures were correlated with appropriate MRI-derived brain structural measures (e.g., dorsolateral prefrontal cortex, frontal eye fields, supplemental eye fields, parietal eye fields, pons, midbrain and cerebellar vermis) and with measures of disease severity and duration. The best discriminators between groups were reflexive saccade gain and the two volitional saccade measures. Gain was also the strongest correlate with disease severity and duration. Most of the Saccadic measures showed strongly significant correlations with neurophysiologically appropriate brain regions. While our patient sample is small, the apparent specificity of these relationships suggests that as new diagnostic methods and treatments become available for NPC, a broader range of Saccadic measures may be useful tools for the assessment of disease progression and treatment efficacy.
