scholarly journals Reliability and correlates of intra-individual variability in the oculomotor system

2019 ◽  
Vol 12 (6) ◽  
Author(s):  
Marlou Nadine Perquin ◽  
Aline Bompas
Keyword(s):  
Pupil Size ◽  
Healthy Subjects ◽  
Statistical Power ◽  
Oculomotor System ◽  
Individual Variability ◽  
Blink Rate ◽  
Individual Traits ◽  
Healthy Participants ◽  
Gaze Position ◽  
Subject Differences

Even if all external circumstances are kept equal, the oculomotor system shows intra-individual variability over time, affecting measures such as microsaccade rate, blink rate, pupil size, and gaze position. Recently, some of these measures have been associated with ADHD on a between-subject level. However, it remains unclear to what extent these measures constitute stable individual traits. In the current study, we investigate the intra-individual reliability of these oculomotor features. Combining results over three experiments (>100 healthy participants), we found evidence for intra-individual reliability over different time points (repeatability) as well as over different conditions (generalization). Furthermore, we correlated oculomotor variability with self-assessed ADHD tendencies, mind wandering, and impulsivity, and found evidence against such correlations. As such, the oculomotor system shows reliable intra-individual reliability, but its use for distinguishing self-assessed individual differences in healthy subjects remains unclear. With our results, we highlight the importance of reliability and statistical power when studying between-subject differences.

scholarly journals Reliability and correlates of intra-individual variability in the oculomotor system

2019 ◽  
Author(s):  
Marlou Nadine Perquin ◽  
Aline Bompas
Keyword(s):  
Pupil Size ◽  
Healthy Subjects ◽  
Statistical Power ◽  
Oculomotor System ◽  
Individual Variability ◽  
Blink Rate ◽  
Individual Traits ◽  
Healthy Participants ◽  
Gaze Position ◽  
Subject Differences

AbstractEven if all external circumstances are kept equal, the oculomotor system shows intra-individual variability over time, affecting measures such as microsaccade rate, blink rate, pupil size, and gaze position. Recently, some of these measures have been associated with ADHD on a between-subject level. However, it remains unclear to what extent these measures constitute stable individual traits. In the current study, we investigate the intra-individual reliability of these oculomotor features. Combining results over three experiments (> 100 healthy participants), we find that most measures show good intra-individual reliability over different time points (repeatability) as well as over different conditions (generalisation). However, we find evidence against any correlation with self-assessed ADHD tendencies, mind wandering, and impulsivity. As such, the oculomotor system shows reliable intra-individual reliability, but its benefit for investigating self-assessed individual differences in healthy subjects remains unclear. With our results, we highlight the importance of reliability and statistical power when studying between-subject differences.

Gait kinematics in Low Back Pain: A non-linear approach

2021 ◽  
pp. 1-8
Author(s):  
Christos Tsigkanos ◽  
Theano Demestiha ◽  
Chara Spiliopoulou ◽  
Georgios Tsigkanos
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Healthy Subjects ◽  
Infrared Camera ◽  
Low Back ◽  
Movement Variability ◽  
Optoelectronic System ◽  
Mean Values ◽  
Non Linear ◽  
Healthy Participants

BACKGROUND: Kinematic analysis has been a dominant tool for addressing the neuromuscular and proprioceptive alterations that occur in Low Back Pain (LBP) patients. Movement variability is a crucial component of this analysis. During the past years a promising approach appears to be the application of non-linear indices. OBJECTIVE: The aim of the study was to compare movement variability, as expressed mainly by non-linear indices, at the pelvis and lumbar between LBP patients and healthy participants during gait. METHODS: Sixteen (16) LBP patients and thirteen (13) healthy control subjects (non-athletes) participated in the study. Participants walked on a treadmill at different walking conditions while recorded by a 6-infrared camera optoelectronic system. Kinematic variability of pelvic and lumbar movement was analyzed using linear (standard deviation) and non-linear indices (Maximal Lyapunov Exponent – LyE and Approximate Entropy – ApEn). RESULTS: Healthy subjects were found to have significantly greater mean values than LBP patients at seven pelvic and lumbar components in LyE, ApEn and SD. Specifically, the calculated LyE at the pelvis during normal gait was proven to have a sensitivity of 92.3% and a specificity of 90% in the discrimination of healthy subjects from LBP patients. Female subjects presented with higher variability in gait measures than males. CONCLUSION: Healthy participants presented with higher movement variability in their kinematic behavior in comparison to LBP patients. Lower variability values may be partly explained by the attempt of LBP patients to avoid painful end of range of motion positions. In this perspective non-linear indices seem to relate to qualitive characteristics of movement that need to be taken into consideration during rehabilitation.

scholarly journals The Brief International Cognitive Assessment in Multiple Sclerosis (BICAMS): Validation in Arabic and Lebanese Normative Values

2021 ◽  
pp. 1-10
Author(s):  
Hala Darwish ◽  
Pia Zeinoun ◽  
Natali Farran ◽  
Husam Ghusn ◽  
Bassem Yamout ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Psychometric Properties ◽  
Cognitive Assessment ◽  
Healthy Subjects ◽  
Good Evidence ◽  
Normative Values ◽  
Arabic Version ◽  
Retest Reliability ◽  
Test Retest Reliability ◽  
Healthy Participants

Abstract Objective: Multiple sclerosis (MS) is often associated with cognitive deficits. Accurate evaluation of the MS patients’ cognitive performance is essential for diagnosis and treatment recommendation. The Brief International Cognitive Assessment in Multiple Sclerosis (BICAMS), widely used cognitive testing battery, examines processing speed, verbal and visuospatial learning, and memory. Our study aims to examine the psychometric properties of an Arabic version of the BICAMS and to provide normative values in a Lebanese sample. Method: The BICAMS, comprised of the Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test-Revised (BVMT-R), and a newly developed verbal learning/memory test, the Verbal Memory Arabic Test (VMAT), were administered on healthy subjects and MS patients. The sample consisted of 180 healthy individuals, of whom 63 were retested after 2–3 weeks. Forty-three MS patients matched with 43 healthy subjects based on age, sex, and years of education were assessed. A sample of 10 MS patients was also examined on two occasions. Test–retest reliability and criterion-related validity were examined, and regression-based norms were derived. Results: The test–retest correlations showed good evidence of reliability with coefficients ranging between 0.64 and 0.73 in the healthy sample, and between 0.43 and 0.92 in the MS sample. The BICAMS was able to discriminate between MS patients and matched healthy participants on the SDMT and BVMT-R. Normative data were comparable to other studies. Conclusions: This new Arabic version of the BICAMS shows initial good psychometric properties. While good evidence of VMAT’s reliability was shown in the healthy participants, less test–retest reliability in this tool was seen in the MS group, and partial criterion-related validity was evident. This renders further examination of the VMAT. We provide regression-based norms for a Lebanese sample and encourage the use of this battery in both research and clinical settings.

scholarly journals Safe and sensible baseline correction of pupil-size data

2017 ◽  
Author(s):  
Sebastiaan Mathôt ◽  
Jasper Fabius ◽  
Elle van Heusden ◽  
Stefan Van der Stigchel
Keyword(s):  
Pupil Size ◽  
Statistical Power ◽  
Baseline Period ◽  
Experimental Manipulation ◽  
Pupillary Response ◽  
Baseline Correction ◽  
Data Loss ◽  
Eye Blinks ◽  
Random Fluctuations ◽  
Size Data

Measurement of pupil size (pupillometry) has recently gained renewed interest from psychologists, but there is little agreement on how pupil-size data is best analyzed. Here we focus on one aspect of pupillometric analyses: baseline correction, that is, analyzing changes in pupil size relative to a baseline period. Baseline correction is useful in experiments that investigate the effect of some experimental manipulation on pupil size. In such experiments, baseline correction improves statistical power by taking into account random fluctuations in pupil size over time. However, we show that baseline correction can also distort data if unrealistically small pupil sizes are recorded during the baseline period, which can easily occur due to eye blinks, data loss, or other distortions. Divisive baseline correction (corrected pupil size = pupil size / baseline) is affected more strongly by such distortions than subtractive baseline correction (corrected pupil size = pupil size - baseline). We make four recommendations for safe and sensible baseline correction of pupil-size data: 1) use subtractive baseline correction; 2) visually compare your corrected and uncorrected data; 3) be wary of pupil-size effects that emerge faster than the latency of the pupillary response allows (within ±220 ms after the manipulation that induces the effect); and 4) remove trials on which baseline pupil size is unrealistically small (indicative of blinks and other distortions).

scholarly journals Improving Accuracy of Brainstem MRI Volumetry: Effects of Age and Sex, and Normalization Strategies

2020 ◽  
Vol 14 ◽  
Author(s):  
Laura Sander ◽  
Antal Horvath ◽  
Simon Pezold ◽  
Simon Andermatt ◽  
Michael Amann ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Healthy Subjects ◽  
Individual Variability ◽  
Intracranial Volume ◽  
Imaging Protocols ◽  
Relative Standard ◽  
Mri Volumetry ◽  
Improving Accuracy ◽  
Age And Sex

Background: Brainstem-mediated functions are impaired in neurodegenerative diseases and aging. Atrophy can be visualized by MRI. This study investigates extrinsic sources of brainstem volume variability, intrinsic sources of anatomical variability, and the influence of age and sex on the brainstem volumes in healthy subjects. We aimed to develop efficient normalization strategies to reduce the effects of intrinsic anatomic variability on brainstem volumetry.Methods: Brainstem segmentation was performed from MPRAGE data using our deep-learning-based brainstem segmentation algorithm MD-GRU. The extrinsic variability of brainstem volume assessments across scanners and protocols was investigated in two groups comprising 11 (median age 33.3 years, 7 women) and 22 healthy subjects (median age 27.6 years, 50% women) scanned twice and compared using Dice scores. Intrinsic anatomical inter-individual variability and age and sex effects on brainstem volumes were assessed in segmentations of 110 healthy subjects (median age 30.9 years, range 18–72 years, 53.6% women) acquired on 1.5T (45%) and 3T (55%) scanners. The association between brainstem volumes and predefined anatomical covariates was studied using Pearson correlations. Anatomical variables with associations of |r| > 0.30 as well as the variables age and sex were used to construct normalization models using backward selection. The effect of the resulting normalization models was assessed by % relative standard deviation reduction and by comparing the inter-individual variability of the normalized brainstem volumes to the non-normalized values using paired t- tests with Bonferroni correction.Results: The extrinsic variability of brainstem volumetry across different field strengths and imaging protocols was low (Dice scores > 0.94). Mean inter-individual variability/SD of total brainstem volumes was 9.8%/7.36. A normalization based on either total intracranial volume (TICV), TICV and age, or v-scale significantly reduced the inter-individual variability of total brainstem volumes compared to non-normalized volumes and similarly reduced the relative standard deviation by about 35%.Conclusion: The extrinsic variability of the novel brainstem segmentation method MD-GRU across different scanners and imaging protocols is very low. Anatomic inter-individual variability of brainstem volumes is substantial. This study presents efficient normalization models for variability reduction in brainstem volumetry in healthy subjects.

scholarly journals Detection of Salivary Interleukin 2 and Interleukin 6 in Patients With Burning Mouth Syndrome

2006 ◽  
Vol 2006 ◽  
pp. 1-4 ◽  
Author(s):  
Daria Simcic ◽  
Sonja Pezelj-Ribaric ◽  
Renata Gržic ◽  
Jelena Horvat ◽  
Gordana Brumini ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Interleukin 2 ◽  
Severity Of Illness ◽  
Burning Mouth Syndrome ◽  
Control Group ◽  
Whole Saliva ◽  
Burning Mouth ◽  
Age Range ◽  
Healthy Participants

The etiology of BMS remains unknown. Role of various cytokines has been implicated in the development of BMS. The aim of this study was to evaluate levels of salivary IL-2 and IL-6 in patients with BMS, compared with age-matched healthy volunteers (control group). Whole saliva from 30 patients with BMS, age range 55–65, was tested for the presence of IL-6 and IL-2 by enzyme immunoassay. Control group consisted of 30 healthy participants, aged 55–65 years. Saliva IL-2 concentrations in BMS were significantly increased in patients compared to healthy subjects: mean34.1±9.7versus7.3±3.0pg/mL;P<.001. Patients with BMS had significantly higher concentrations of IL-6 compared to control: mean30.8±5.6versus5.2±2.8pg/mL;P<.001. In patients with BMS, IL-2 and IL-6 levels in saliva are elevated, correlating with the severity of illness.

scholarly journals Eye Gaze Correlates of Motor Impairment in VR Observation of Motor Actions

2016 ◽  
Vol 55 (01) ◽  
pp. 79-83 ◽  
Author(s):  
A. Vourvopoulos ◽  
A. Bernardino ◽  
i Bermúdez Badia ◽  
J. Alves
Keyword(s):  
Virtual Reality ◽  
Smooth Pursuit ◽  
Healthy Subjects ◽  
Eye Gaze ◽  
Action Observation ◽  
Motor Impairment ◽  
Motor Deficits ◽  
Stroke Patients ◽  
Motor Actions ◽  
Healthy Participants

Summary Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Methodologies, Models and Algorithms for Patients Rehabilitation”. Objective: Identify eye gaze correlates of motor impairment in a virtual reality motor observation task in a study with healthy participants and stroke patients. Methods: Participants consisted of a group of healthy subjects (N = 20) and a group of stroke survivors (N = 10). Both groups were required to observe a simple reach-and-grab and place-and-release task in a virtual environment. Additionally, healthy subjects were required to observe the task in a normal condition and a constrained movement condition. Eye movements were recorded during the observation task for later analysis. Results: For healthy participants, results showed differences in gaze metrics when comparing the normal and arm-constrained conditions. Differences in gaze metrics were also found when comparing dominant and non-dominant arm for saccades and smooth pursuit events. For stroke patients, results showed longer smooth pursuit segments in action observation when observing the paretic arm, thus providing evidence that the affected circuitry may be activated for eye gaze control during observation of the simulated motor action. Conclusions: This study suggests that neural motor circuits are involved, at multiple levels, in observation of motor actions displayed in a virtual reality environment. Thus, eye tracking combined with action observation tasks in a virtual reality display can be used to monitor motor deficits derived from stroke, and consequently can also be used for re -habilitation of stroke patients.

scholarly journals Pupil Function in Pseudophakia: Proximal Miosis Behavior and Optical Influence

Photonics ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 114 ◽  
Author(s):  
Elsa Fonseca ◽  
Paulo Fiadeiro ◽  
Renato Gomes ◽  
Angel Sanchez Trancon ◽  
António Baptista ◽  
...  
Keyword(s):  
Pupil Size ◽  
Angular Size ◽  
Optical Quality ◽  
Individual Variability ◽  
Computer Simulation Model ◽  
Small Contribution ◽  
Distant Object ◽  
Object Distance ◽  
The Mean ◽  
The Impact

The pseudophakic eye lacks the ability to produce a refractive change in response to object proximity. Thus, individual anatomical features such as the pupil size play an important role in achieving functional vision levels. In this work, the range of pupil sizes at varying object distance was measured in pseudophakic participants. Furthermore, the impact of the measured values on eye optical quality was investigated using a computer simulation model. A binocular eye-tracker was used to measure the participants’ pupil sizes at six object distances, ranging from 0.33 m (i.e., vergence of 3.00 D) to 3.00 m (i.e., vergence of 0.33 D), while observing a Maltese cross with a constant angular size of 1 ∘ . In total, 58 pseudophakic participants were enrolled in this study (age mean ± standard deviation: 70.5 ± 11.3 years). The effects of object distance and age on pupil size variation were investigated using linear mixed effects regression models. Age was found to have a small contribution to individual variability. The mean infinite distance pupil size (intercept) was 4.45 ( 95 % CI: 2.74, 6.17) mm and the mean proximal miosis (slope) was − 0.23 ( 95 % CI: −0.53, 0.08) mm/D. The visual acuity (VA) estimation for a distant object ranged from − 0.1 logMAR (smallest pupil) to 0.04 logMAR (largest pupil) and the near VA ( 0.33 m) when mean proximal miosis was considered ranged from 0.28 logMAR (smallest pupil) to 0.42 logMAR (largest pupil). When mean distance pupil was considered, proximal miosis individual variability produced a variation of 0.04 logMAR for the near object and negligible variation for the distant object. These results support the importance of distance pupil size measurement for the prediction of visual performance in pseudophakia, while suggesting that proximal miosis has a negligible impact in VA variability.

scholarly journals Understanding Inter-Individual Variability in Monoclonal Antibody Disposition

Antibodies ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 56 ◽  
Author(s):  
Veena A. Thomas ◽  
Joseph P. Balthasar
Keyword(s):  
Individual Variability ◽  
Population Pharmacokinetic ◽  
Population Pharmacokinetic Modeling ◽  
Dominant Class ◽  
Physiological Relevance ◽  
Underlying Mechanisms ◽  
Preclinical And Clinical Studies ◽  
Subject Differences

Monoclonal antibodies (mAbs) are currently the largest and most dominant class of therapeutic proteins. Inter-individual variability has been observed for several mAbs; however, an understanding of the underlying mechanisms and factors contributing to inter-subject differences in mAb disposition is still lacking. In this review, we analyze the mechanisms of antibody disposition and the putative mechanistic determinants of inter-individual variability. Results from in vitro, preclinical, and clinical studies were reviewed evaluate the role of the neonatal Fc receptor and Fc gamma receptors (expression and polymorphism), target properties (expression, shedding, turnover, internalization, heterogeneity, polymorphism), and the influence of anti-drug antibodies. Particular attention is given to the influence of co-administered drugs and disease, and to the physiological relevance of covariates identified by population pharmacokinetic modeling, as determinants of variability in mAb pharmacokinetics.

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