Volume of confidence ellipsoid: a technique for quantifying trunk sway during stance

2015 ◽  
Vol 60 (2) ◽  
Author(s):  
Patrik Kutilek ◽  
Ondrej Cakrt ◽  
Vladimir Socha ◽  
Karel Hana
Keyword(s):  
Healthy Subjects ◽  
Three Dimensional ◽  
Principal Component ◽  
Eyes Closed ◽  
Trunk Sway ◽  
Eyes Open ◽  
Ellipsoid Volume ◽  
Three Degree Of Freedom ◽  
Balance Problems ◽  
Confidence Ellipsoid

AbstractThe position of the trunk can be negatively affected by many diseases. This work focuses on a noninvasive method of quantifying human postural stability and identifying defects in balance and coordination as a result of the nervous system pathology. We used a three-degree-of-freedom orientation tracker (Xsens MTx unit) placed on a patient’s trunk and measured three-dimensional (3-D) data (pitch, roll, and yaw) during quiet stance. The principal component analysis was used to analyze the data and to determine the volume of 3-D 95% confidence ellipsoid. Using this method, we were able to model the distribution of the measured 3-D data (pitch, roll, and yaw). Eight patients with degenerative cerebellar disease and eight healthy subjects in this study were measured during stance, with eyes open and eyes closed, and statistical analysis was performed. The results of the new method based on the 3-D confidence ellipsoid show that the volumes related to the patients are significantly larger than the volumes related to the healthy subjects. The concept of confidence ellipsoid volume, although known to the biomechanics community, has not been used before to study the postural balance problems. The method can also be used to study, for example, head and pelvis movements or alignments during stance.

Measurements of Trunk Sway for Stance and Gait Tasks 2 Years after Vestibular Neurectomy

2018 ◽  
Vol 23 (5) ◽  
pp. 298-308 ◽  
Author(s):  
Dominique Vibert ◽  
John H.J. Allum ◽  
Martin Kompis ◽  
Simona Wiedmer ◽  
Christof Stieger ◽  
...  
Keyword(s):  
Balance Control ◽  
Recovery Period ◽  
Subjective Assessment ◽  
Vestibular Neurectomy ◽  
Eyes Closed ◽  
Before And After ◽  
Task Durations ◽  
Trunk Sway ◽  
Central Compensation ◽  
Balance Problems

The aim of this study was to investigate changes in balance control for stance and gait tasks in patients 2 years before and after vestibular neurectomy (VN) performed to alleviate intractable Meniere’s disease. Amplitudes of trunk sway in roll and pitch directions were measured for stance and gait tasks in 19 patients using gyroscopes mounted at the lower-back. Measurements before VN and 2 years later were compared to those of healthy age-matched controls (HC). We also examined if changes in trunk sway amplitudes were correlated with patients’ subjective assessment of disability using the AAO-HNS scale. For patients with low AAO-HNS scores 0–2 (n = 14), trunk roll and pitch sway velocities, standing eyes closed on foam, increased 2 years post VN compared to HC values (p < 0.01). Trunk sway amplitudes remained at levels of HC for simple gait tasks, but task durations were longer and therefore gait slower. For complex gait tasks (stairs), balance control remained impaired at 2 years. In patients with AAO-HNS high scores level 6 (n = 5), balance control remained abnormal, compared to HC, 2 years postoperatively for all stance, several simple and all complex gait tasks. Trunk sway in the pitch and roll directions for stance tasks was correlated with clinical (AAO-HNS) scores (p ≤ 0.05). These results indicate that VN leads to chronic balance problems for stance and complex gait tasks. The problems are greater for patients with high compared to low AAO-HNS scores, thereby explaining the different symptoms reported by these patients. The lack of balance recovery in VN patients to levels of HCs after 2 years contrasts with the 3 months average recovery period for acute vestibular neuritis patients and is indicative of the effects of neurectomy on central compensation processes.

scholarly journals On the Operational Utility of Measures of EEG Integrated Information

2021 ◽  
Author(s):  
David Darmon ◽  
Tomas Watanabe ◽  
Christopher Cellucci ◽  
Paul E Rapp
Keyword(s):  
Principal Component ◽  
Information Criterion ◽  
Model Order ◽  
Information Measures ◽  
Eyes Closed ◽  
Condition Effect ◽  
Eyes Open ◽  
Open Versus ◽  
Healthy Participants ◽  
Integrated Information

Multichannel EEGs were obtained from healthy participants in the eyes-closed no-task condition (where the alpha component is typically abolished). EEG dynamics in the two conditions were quantified with two related binary Lempel-Ziv measures of the first principal component and with three measures of integrated information including the more recently proposed integrated synergy. Both integrated information and integrated synergy with model order p=1 had greater values in the eyes closed condition. If the model order of integrated synergy was determined with the Bayesian Information Criterion, this pattern was reversed, and in common with other measures, integrated synergy was greater in the eyes open condition. Eyes open versus eyes closed separation was quantified by calculation of the between-condition effect size. Lempel-Ziv complexity of the first principal component showed greater separation than the measures of integrated information. The performance of the integrated information measures investigated here when distinguishing between indisputably different physiological states encourages caution when advocating for their use as measures of consciousness.

QUANTITATIVE CHARACTERIZATION OF THE COMPLEXITY OF MULTICHANNEL HUMAN EEGS

2005 ◽  
Vol 15 (05) ◽  
pp. 1737-1744 ◽  
Author(s):  
P. E. RAPP ◽  
C. J. CELLUCCI ◽  
T. A. A. WATANABE ◽  
A. M. ALBANO
Keyword(s):  
Standard Deviation ◽  
Principal Component ◽  
Algorithmic Complexity ◽  
Time Dependent ◽  
Quantitative Characterization ◽  
Complexity Measures ◽  
Eyes Closed ◽  
Multichannel Signals ◽  
Eyes Open

In this contribution, eleven different measures of the complexity of multichannel EEGs are described, and their effectiveness in discriminating between two behavioral conditions (eyes open resting versus eyes closed resting) is compared. Ten of the methods were variants of the algorithmic complexity and the covariance complexity. The eleventh measure was a multivariate complexity measure proposed by Tononi and Edelman. The most significant between-condition change was observed with Tononi–Edelman complexity which decreased in the eyes open condition. Of the algorithmic complexity measures tested, the binary Lempel–Ziv complexity and the binary Lempel–Ziv redundancy of the first principal component following mean normalization and normalization against the standard deviation gave the most significant between-group discrimination. A time-dependent generalization of the covariance complexity that can be applied to nonstationary multichannel signals is also described.

scholarly journals Should the Minimal Intervention Principle Be Considered When Investigating Dual-Tasking Effects on Postural Control?

2019 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
Felix Wachholz ◽  
Federico Tiribello ◽  
Arunee Promsri ◽  
Peter Federolf
Keyword(s):  
Postural Control ◽  
Center Of Pressure ◽  
Force Plate ◽  
Principal Component ◽  
Mean Velocity ◽  
Dual Tasking ◽  
Minimal Intervention ◽  
Eyes Closed ◽  
Eyes Open ◽  
Postural Movement

Dual-tasking charges the sensorimotor system with performing two tasks simultaneously. Center of pressure (COP) analysis reveals the postural control that is altered during dual-tasking, but may not reveal the underlying neural mechanisms. In the current study, we hypothesized that the minimal intervention principle (MIP) provides a concept by which dual-tasking effects on the organization and prioritization of postural control can be predicted. Postural movements of 23 adolescents (age 12.7 ± 1.3; 8 females) and 15 adults (26.9 ± 2.3) were measured in a bipedal stance with eyes open, eyes closed and eyes open while performing a dual-task using a force plate and 39 reflective markers. COP data was analyzed by calculating the mean velocity, standard deviation and amplitude of displacement. Kinematic data was examined by performing a principal component analysis (PCA) and extracting postural movement components. Two variables were determined to investigate changes in amplitude (aVark) and in control (Nk) of the principal movement components. Results in aVark and in Nk agreed well with the predicted dual-tasking effects. Thus, the current study corroborates the notion that the MIP should be considered when investigating postural control under dual-tasking conditions.

scholarly journals On the Operational Utility of Measures of Multichannel EEGs

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1434
Author(s):  
David Darmon ◽  
Tomas Watanabe ◽  
Christopher Cellucci ◽  
Paul E. Rapp
Keyword(s):  
Principal Component ◽  
Information Criterion ◽  
Task Condition ◽  
Model Order ◽  
Eyes Closed ◽  
Condition Effect ◽  
Eyes Open ◽  
Open Versus ◽  
Healthy Participants ◽  
Integrated Information

Multichannel EEGs were obtained from healthy participants in the eyes-closed no-task condition and in the eyes-open condition (where the alpha component is typically abolished). EEG dynamics in the two conditions were quantified with two related binary Lempel–Ziv measures of the first principal component, and with three measures of integrated information, including the more recently proposed integrated synergy. Both integrated information and integrated synergy with model order p=1 had greater values in the eyes-closed condition. When the model order of integrated synergy was determined with the Bayesian Information Criterion, this pattern was reversed, and in line with the other measures, integrated synergy was greater in the eyes-open condition. Eyes-open versus eyes-closed separation was quantified by calculating the between-condition effect size. The Lempel–Ziv complexity of the first principal component showed greater separation than the measures of integrated information.

scholarly journals EEG study of visual reactivity in aphasic patients

2013 ◽  
Vol 60 (3) ◽  
pp. 45-56
Author(s):  
Biljana Stojanovic ◽  
Ljubomir Djurasic ◽  
Stevan Jovic ◽  
Dalibor Paspalj
Keyword(s):  
Frequency Analysis ◽  
Healthy Subjects ◽  
Speech Therapy ◽  
Quantitative Eeg ◽  
Brain Regions ◽  
Rehabilitative Treatment ◽  
Quality Of Recovery ◽  
Eyes Closed ◽  
Coefficients Of Variation ◽  
Eyes Open

AIM: to compare patients with good and poor recovery after 1 and 3 months from onset of poststroke aphasia and to correlate the quality of recovery with quantitative EEG (QEEG) measures (frequency analysis with the limits of variability, and index of asymmetry). METHODS: The investigation was performed on the sample of 32 patients with poststroke aphasia, 15 females (46.88%) and 17 males (53.12%), mean age + standard deviation (SD) being 50.65+9.93 years. QEEG measures of this sample were compared with those in a group of 86 healthy controls, 39 (45.35%) females and 47 (54,65%) males, mean age +SD being 51.08+10.08 years. Frequency analysis was performed in eyes closed and eyes open conditions in both controls and in aphasics who were tested just before and two month after rehabilitative treatment with speech therapy. RESULTS: We have got normal distribution for all derivations and all frequency bands in the group of healthy subjects. On the basis of this finding, we determined coefficients of variation in patients with poststroke aphasia and discovered that their maximal variability scores were significantly decreased. Compared to healthy subjects, the index of asymmetry between two hemispheres and between main brain regions was significantly higher in the aphasic patients than in controls. However, the differences in the index of asymmetry and limits of variability significantly decreased after two month treatment in the subgroup of patients with good improvement compared with the subgroup of patients with poor improvement of poststroke aphasia. CONCLUSION: QEEG measures may have predicitive value in post-stroke aphasia.

A Contribution by Multidimensional Methods to Choosing Descriptive Data for EEG by Spectral Analysis

1976 ◽  
Vol 15 (04) ◽  
pp. 229-236 ◽  
Author(s):  
M. Chavance ◽  
Dominique Samson-Dollfus
Keyword(s):  
Spectral Analysis ◽  
Power Spectra ◽  
Principal Component ◽  
Partial Reduction ◽  
Descriptive Data ◽  
Normal Children ◽  
Simple Arithmetic ◽  
Eyes Closed ◽  
Eyes Open ◽  
Multidimensional Methods

One of the main difficulties in automatic analysis of EEG tracings is the reduction of data; spectral analysis allows only a partial reduction. Principal component analysis is used to determine amongst a group of quantitative variables those which best describe a given sample of power spectra. The tracings come from normal children (10 to 12 years of age) recorded on four leads (fronto-central right and left, centro-occipital right and left) in five experimental situations (resting with eyes closed, during five minutes of hyperventilation, resting with eyes open, and during simple arithmetic and vocabulary tests, eyes closed). It is shown that four variables are enough to describe the spectra.

scholarly journals ASSESSMENT OF POSTURAL INSTABILITY IN PATIENTS WITH A NEUROLOGICAL DISORDER USING A TRI-AXIAL ACCELEROMETER

2015 ◽  
Vol 55 (4) ◽  
pp. 229 ◽  
Author(s):  
Lenka Hanakova ◽  
Vladimir Socha ◽  
Jakub Schlenker ◽  
Ondrej Cakrt ◽  
Patrik Kutilek
Keyword(s):  
Neurological Disorder ◽  
Postural Stability ◽  
Healthy Subjects ◽  
Quantitative Method ◽  
Balance Control ◽  
Three Dimensional ◽  
Quiet Standing ◽  
Progressive Cerebellar Ataxia ◽  
Set Of Points ◽  
Confidence Ellipsoid

<span lang="EN-US">Current techniques for quantifying human postural stability during quiet standing have several limitations. The main problem is that only two movement variables are evaluated, though a better description of complex three-dimensional (3-D) movements can be provided with the use of three variables. A single tri-axial accelerometer placed on the trunk was used to measure 3-D data.<br />We are able to evaluate 3-D movements using a method based on the volume of confidence ellipsoid (VE) of the set of points obtained by plotting three accelerations against each other. Our method was used to identify and evaluate pathological balance control. In this study, measurements were made of patients with progressive cerebellar ataxia, and also control measurements of healthy subjects, and a statistical analysis was performed. The results show that the VEs of the neurological disorder patients are significantly larger than the VEs of the healthy subjects. It can be seen that the quantitative method based on VE is very sensitive for identifying changes in stability, and that it is able to distinguish between neurological disorder patients and healthy subjects.<br /></span>

scholarly journals Adolescent Awkwardness: Alterations in Temporal Control Characteristics of Posture with Maturation and the Relation to Movement Exploration

2020 ◽  
Vol 10 (4) ◽  
pp. 216 ◽  
Author(s):  
Felix Wachholz ◽  
Federico Tiribello ◽  
Maurice Mohr ◽  
Steven van Andel ◽  
Peter Federolf
Keyword(s):  
Motor Control ◽  
Body Height ◽  
Age Groups ◽  
Principal Component ◽  
Developmental Phase ◽  
Processing Times ◽  
Eyes Closed ◽  
Coordinative Structure ◽  
Eyes Open ◽  
Underlying Mechanisms

A phenomenon called adolescent awkwardness is believed to alter motor control, but underlying mechanisms remain largely unclear. Since adolescents undergo neurological and anthropometrical changes during this developmental phase, we hypothesized that adolescents control their movements less tightly and use a different coordinative structure compared to adults. Moreover, we tested if emerging differences were driven by body height alterations between age groups. Using 39 reflective markers, postural movements during tandem stance with eyes open and eyes closed of 12 adolescents (height 168.1 ± 8.8 cm) and 14 adults were measured, in which 9 adults were smaller or equal than 180 cm (177.9 ± 3.0 cm) and 5 taller or equal than 190 cm (192.0 ± 2.5 cm). A principal component analysis (PCA) was used to extract the first nine principal movement components (PMk). The contribution of each PMk to the overall balancing movement was determined according to their relative variance share (rVARk) and tightness of motor control was examined using the number of times that the acceleration of each PMk changed direction (Nk). Results in rVARk did not show significant differences in coordinative structure between adolescents and adults, but Nk revealed that adolescents seem to control their movements less tightly in higher-order PMk, arguably due to slower processing times and missing automatization of postural control or potential increases in exploration. Body height was found to not cause motor control differences between age groups.

scholarly journals Gait Assessment Using Three-Dimensional Acceleration of the Trunk in Idiopathic Normal Pressure Hydrocephalus

2021 ◽  
Vol 13 ◽  
Author(s):  
Shigeki Yamada ◽  
Yukihiko Aoyagi ◽  
Masatsune Ishikawa ◽  
Makoto Yamaguchi ◽  
Kazuo Yamamoto ◽  
...  
Keyword(s):  
Normal Pressure Hydrocephalus ◽  
Three Dimensional ◽  
Normal Pressure ◽  
Lateral Acceleration ◽  
Vertical Acceleration ◽  
Gait Features ◽  
Trunk Acceleration ◽  
Ellipsoid Volume ◽  
Pathological Gait ◽  
Confidence Ellipsoid

Background: The subjective evaluation of pathological gait exhibits a low inter-rater reliability. Therefore, we developed a three-dimensional acceleration of the trunk during walking to assess the pathological gait quantitatively.Methods: We evaluated 97 patients who underwent the cerebrospinal tap test and were diagnosed with idiopathic normal pressure hydrocephalus (iNPH) and 68 healthy elderlies. The gait features of all patients were evaluated and classified as one of the following: freezing of gait, wide-based gait, short-stepped gait, shuffling gait, instability, gait festination, difficulty in changing direction, and balance disorder in standing up. All gait features of 68 healthy elderlies were treated as normal. Trunk acceleration was recorded automatically by a smartphone placed on the umbilicus during a 15-foot walking test. Two novel indices were created. The first index was a trunk acceleration index, which was defined as (forward acceleration fluctuation) + (vertical acceleration fluctuation) – (lateral acceleration fluctuation) based on the multivariate logistics regression model, and the second index was created by multiplying the forward acceleration with the vertical acceleration. Additionally, 95% confidence ellipsoid volume of the three-dimensional accelerations was assessed.Results: Forward and vertical acceleration fluctuations were significantly associated with the probability of an iNPH-specific pathological gait. The trunk acceleration index demonstrated the strongest association with the probability of an iNPH-specific pathological gait. The areas under the receiver-operating characteristic curves for detecting 100% probability of an iNPH-specific pathological gait were 86.9% for forward acceleration fluctuation, 88.0% for vertical acceleration fluctuation, 82.8% for lateral acceleration fluctuation, 89.0% for trunk acceleration index, 88.8% for forward × vertical acceleration fluctuation, and 87.8% for 95% confidence ellipsoid volume of the three-dimensional accelerations.Conclusions: The probability of a pathological gait specific to iNPH is high at the trunk acceleration fluctuation, reduced in the forward and vertical directions, and increased in the lateral direction.

Sign in / Sign up

Export Citation Format

Share Document