scholarly journals A Novel Framework for Quantifying Accuracy and Precision of Event Detection Algorithms in FES-Cycling

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4571
Author(s):  
Ronan Le Guillou ◽  
Martin Schmoll ◽  
Benoît Sijobert ◽  
David Lobato Borges ◽  
Emerson Fachin-Martins ◽  
...  
Keyword(s):  
Event Detection ◽  
Gait Cycle ◽  
Concordance Correlation ◽  
Activation Patterns ◽  
Detection Algorithms ◽  
Accuracy And Precision ◽  
Crank Angle ◽  
Cord Injury ◽  
Triggering Events ◽  
Seating Position

Functional electrical stimulation (FES) is a technique used in rehabilitation, allowing the recreation or facilitation of a movement or function, by electrically inducing the activation of targeted muscles. FES during cycling often uses activation patterns which are based on the crank angle of the pedals. Dynamic changes in their underlying predefined geometrical models (e.g., change in seating position) can lead to desynchronised contractions. Adaptive algorithms with a real-time interpretation of anatomical segments can avoid this and open new possibilities for the automatic design of stimulation patterns. However, their ability to accurately and precisely detect stimulation triggering events has to be evaluated in order to ensure their adaptability to real-case applications in various conditions. In this study, three algorithms (Hilbert, BSgonio, and Gait Cycle Index (GCI) Observer) were evaluated on passive cycling inertial data of six participants with spinal cord injury (SCI). For standardised comparison, a linear phase reference baseline was used to define target events (i.e., 10%, 40%, 60%, and 90% of the cycle’s progress). Limits of agreement (LoA) of ±10% of the cycle’s duration and Lin’s concordance correlation coefficient (CCC) were used to evaluate the accuracy and precision of the algorithm’s event detections. The delays in the detection were determined for each algorithm over 780 events. Analysis showed that the Hilbert and BSgonio algorithms validated the selected criteria (LoA: +5.17/−6.34% and +2.25/−2.51%, respectively), while the GCI Observer did not (LoA: +8.59/−27.89%). When evaluating control algorithms, it is paramount to define appropriate criteria in the context of the targeted practical application. To this end, normalising delays in event detection to the cycle’s duration enables the use of a criterion that stays invariable to changes in cadence. Lin’s CCC, comparing both linear correlation and strength of agreement between methods, also provides a reliable way of confirming comparisons between new control methods and an existing reference.

scholarly journals Brain fMRI during orientation selective epidural spinal cord stimulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Antonietta Canna ◽  
Lauri J. Lehto ◽  
Lin Wu ◽  
Sheng Sang ◽  
Hanne Laakso ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Stimulation ◽  
Pain Treatment ◽  
Positive Impact ◽  
Sensory Information ◽  
Activation Patterns ◽  
Promising Tool ◽  
Cord Injury ◽  
Epidural Spinal Cord Stimulation ◽  
Brain Fmri

AbstractEpidural spinal cord stimulation (ESCS) is widely used for chronic pain treatment, and is also a promising tool for restoring motor function after spinal cord injury. Despite significant positive impact of ESCS, currently available protocols provide limited specificity and efficiency partially due to the limited number of contacts of the leads and to the limited flexibility to vary the spatial distribution of the stimulation field in respect to the spinal cord. Recently, we introduced Orientation Selective (OS) stimulation strategies for deep brain stimulation, and demonstrated their selectivity in rats using functional MRI (fMRI). The method achieves orientation selectivity by controlling the main direction of the electric field gradients using individually driven channels. Here, we introduced a similar OS approach for ESCS, and demonstrated orientation dependent brain activations as detected by brain fMRI. The fMRI activation patterns during spinal cord stimulation demonstrated the complexity of brain networks stimulated by OS-ESCS paradigms, involving brain areas responsible for the transmission of the motor and sensory information. The OS approach may allow targeting ESCS to spinal fibers of different orientations, ultimately making stimulation less dependent on the precision of the electrode implantation.

Validation of heart rate measurement of Fitbit Charge 4 and Xiaomi Mi Band 5 (Preprint)

2021 ◽  
Author(s):  
Magdalena Jachymek ◽  
Michał Tomasz Jachymek ◽  
Radosław Marek Kiedrowicz ◽  
Jarosław Kaźmierczak ◽  
Małgorzata Peregud-Pogorzelska
Keyword(s):  
Heart Rate ◽  
Stress Test ◽  
Absolute Error ◽  
Sensor Technology ◽  
Concordance Correlation ◽  
Accuracy And Precision ◽  
Validation Criteria ◽  
Precision And Accuracy ◽  
Fitness Trackers ◽  
Error Percentage

BACKGROUND Recent advances in mobile sensor technology have led to increased popularity of wrist-worn fitness trackers. The possibility to use a smartwatch as a rehabilitation tool to monitor patients’ heart rate during exercise has won the attention of many researchers. OBJECTIVE The aim of the study was to evaluate the accuracy and precision of HR measurement performed by two wrist monitors: Fitbit Charge 4 (Fitbit) and Xiaomi Mi Band 5 (Xiaomi). METHODS 31 healthy volunteers were asked to perform a stress test on a treadmill. During the test their heart rate was recorded simultaneously by both wristbands and ECG at 1minute intervals. The mean absolute error percentage (MAPE), Lin’s concordance correlation coefficient (LCCC) and Bland-Altman were calculated to compare precision and accuracy of heart rate measurements. The estimated validation criteria were MAPE < 10% and LCCC < .8 RESULTS The overall MAPE of the Fitbit device was 10.19% (±11.79%) and the MAPE of Xiaomi was (6.89 % ± 9.75). LCCC of Fitbit HR measurements was .753 (95% CI:0.717-0.785) and of Xiaomi – .903 (0.886-0.917). In both devices the precision and accuracy were decreasing with the increasing exercise intensity. Age, sex, height, weight, BMI did not influence the accuracy of both devices. CONCLUSIONS The accuracy of a wearable wrist-worn heart rate monitor varies and depends on the intensity of training. The decision concerning the application of such a device as a monitor during in-home rehabilitation should be taken with caution, as it may prove not reliable enough.

The Human Central Pattern Generator for Locomotion: Does It Exist and Contribute to Walking?

2017 ◽  
Vol 23 (6) ◽  
pp. 649-663 ◽  
Author(s):  
Karen Minassian ◽  
Ursula S. Hofstoetter ◽  
Florin Dzeladini ◽  
Pierre A. Guertin ◽  
Auke Ijspeert
Keyword(s):  
Spinal Cord ◽  
Neural Control ◽  
Muscle Activation ◽  
Central Pattern Generators ◽  
Lumbar Spinal Cord ◽  
Step Cycle ◽  
Experimental Conditions ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Cord Injury

The ability of dedicated spinal circuits, referred to as central pattern generators (CPGs), to produce the basic rhythm and neural activation patterns underlying locomotion can be demonstrated under specific experimental conditions in reduced animal preparations. The existence of CPGs in humans is a matter of debate. Equally elusive is the contribution of CPGs to normal bipedal locomotion. To address these points, we focus on human studies that utilized spinal cord stimulation or pharmacological neuromodulation to generate rhythmic activity in individuals with spinal cord injury, and on neuromechanical modeling of human locomotion. In the absence of volitional motor control and step-specific sensory feedback, the human lumbar spinal cord can produce rhythmic muscle activation patterns that closely resemble CPG-induced neural activity of the isolated animal spinal cord. In this sense, CPGs in humans can be defined by the activity they produce. During normal locomotion, CPGs could contribute to the activation patterns during specific phases of the step cycle and simplify supraspinal control of step cycle frequency as a feedforward component to achieve a targeted speed. Determining how the human CPGs operate will be essential to advance the theory of neural control of locomotion and develop new locomotor neurorehabilitation paradigms.

scholarly journals Changes in Locomotor Muscle Activity After Treadmill Training in Subjects With Incomplete Spinal Cord Injury

2009 ◽  
Vol 101 (2) ◽  
pp. 969-979 ◽  
Author(s):  
Monica A. Gorassini ◽  
Jonathan A. Norton ◽  
Jennifer Nevett-Duchcherer ◽  
Francois D. Roy ◽  
Jaynie F. Yang
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Treadmill Training ◽  
Emg Activity ◽  
Incomplete Spinal Cord Injury ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Cord Injury

Intensive treadmill training after incomplete spinal cord injury can improve functional walking abilities. To determine the changes in muscle activation patterns that are associated with improvements in walking, we measured the electromyography (EMG) of leg muscles in 17 individuals with incomplete spinal cord injury during similar walking conditions both before and after training. Specific differences were observed between subjects that eventually gained functional improvements in overground walking (responders), compared with subjects where treadmill training was ineffective (nonresponders). Although both groups developed a more regular and less clonic EMG pattern on the treadmill, it was only the tibialis anterior and hamstring muscles in the responders that displayed increases in EMG activation. Likewise, only the responders demonstrated decreases in burst duration and cocontraction of proximal (hamstrings and quadriceps) muscle activity. Surprisingly, the proximal muscle activity in the responders, unlike nonresponders, was three- to fourfold greater than that in uninjured control subjects walking at similar speeds and level of body weight support, suggesting that the ability to modify muscle activation patterns after injury may predict the ability of subjects to further compensate in response to motor training. In summary, increases in the amount and decreases in the duration of EMG activity of specific muscles are associated with functional recovery of walking skills after treadmill training in subjects that are able to modify muscle activity patterns following incomplete spinal cord injury.

scholarly journals Standard area diagram set for bacterial spot assessment in fruits of yellow passion fruit

2018 ◽  
Vol 40 (6) ◽  
Author(s):  
Anne Pinheiro Costa ◽  
Márcio de Carvalho Pires ◽  
José Ricardo Peixoto ◽  
Luiz Eduardo Bassay Blum ◽  
Fábio Gelape Faleiro
Keyword(s):  
Systematic Errors ◽  
Passion Fruit ◽  
Coefficient Of Determination ◽  
Concordance Correlation Coefficient ◽  
Simple Linear Regression ◽  
Concordance Correlation ◽  
Bacterial Spot ◽  
Passiflora Edulis ◽  
Accuracy And Precision ◽  
Yellow Passion Fruit

Abstract This study developed and validated a standard area diagram set (SADs) for severity assessment of bacterial spot (Xanthomonas axonopodis pv. ) in passifloraefruits of yellow passion fruit (Passiflora edulis). The SADs consisted of eight severity levels (1%; 3%; 5%; 10%; 21%; 38%; 65%; and 80%). For its validation, 20 raters, who initially estimated the disease severity without the aid of the SADs, were divided into groups (G1 and G3, inexperienced; G2 and G4, experienced). Subsequently, G1 and G2 performed the second evaluation without the proposed SADs, and G3 and G4 completed the second evaluation using the proposed SADs. The accuracy and precision of the assessments were determined by simple linear regression and by the Lin’s concordance correlation coefficient. The increase in the accuracy was confirmed by the reduction in the constant and systematic errors, indicating that the estimated severities were close to the actual values when the SADs was used. Inexperienced raters benefited the most from the use of the SADs, and 60% and 100% of them presented constant and systematic error-free estimates, respectively. Precision increased with the increase in the coefficient of determination, the reduction in absolute errors, and the increase in the reproducibility of the estimates between pairs of raters.

MODELING AND SIMULATING HETEROGENEOUS HYBRID SYSTEMS IN ISMA 2021

2021 ◽  
pp. 12-17
Author(s):  
Е.А. Попов
Keyword(s):  
Modeling And Simulation ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Event Detection ◽  
Internal Representation ◽  
Simulation Environment ◽  
Detection Algorithms

Разработаны алгоритмы обнаружения событий в гетерогенных гибридных системах. Представлена архитектура новой инструментальной среды ИСМА 2021. Приведено универсальное внутреннее представление гетерогенных гибридных систем. Рассмотрен пример расчёта классической гибридной системы в ИСМА 2021. Event detection algorithms for heterogeneous hybrid systems are designed. The architecture of the new modeling and simulation environment ISMA 2021 is presented. The universal internal representation of heterogeneous hybrid systems is given. A classic hybrid system is simulated in ISMA 2021.

scholarly journals Cortical reorganization in patients with cervical spondylotic myelopathy

2007 ◽  
Vol 6 (6) ◽  
pp. 544-551 ◽  
Author(s):  
Langston T. Holly ◽  
Yun Dong ◽  
Richard Albistegui-Dubois ◽  
Jonathan Marehbian ◽  
Bruce Dobkin
Keyword(s):  
Healthy Volunteers ◽  
Cervical Spondylotic Myelopathy ◽  
Surgical Intervention ◽  
Neurological Function ◽  
Cortical Reorganization ◽  
Cortical Activation ◽  
Cortical Representation ◽  
Activation Patterns ◽  
Cord Injury ◽  
Before And After

Object Recent investigations have demonstrated that the cerebral cortex can reorganize as a result of spinal cord injury and may play a role in preserving neurological function. Reorganization of cortical representational maps in patients with cervical spondylotic myelopathy (CSM) has not been previously described. The authors sought to determine the feasibility of using functional magnetic resonance (fMR) imaging in patients with CSM to investigate changes in the cortical representation of the wrist and ankle before and after surgical intervention. Methods Four patients with clinical and imaging evidence of CSM were prospectively enrolled in this study. The patients underwent preoperative neurological examination, functional assessment, cervical imaging, and brain fMR imaging. The fMR imaging activation task undertaken was either wrist extension or ankle dorsiflexion, depending on whether the patient's primary impairment was hand dysfunction or gait difficulty. The cohort then underwent further evaluations at 6 weeks and 3 and 6 months postoperatively. In addition, five healthy volunteers underwent fMR imaging at two different time points and served as controls. In the healthy volunteers fMR imaging demonstrated areas of focal cortical activation limited to the contralateral primary motor area for the assigned motor tasks; the activation patterns were stable throughout repeated imaging. In comparison, in patients with CSM fMR imaging demonstrated expansion of the cortical representation of the affected extremity. Surgical decompression resulted in improvements in neurological function and reorganization of the representational map. Conclusions The findings of this preliminary study demonstrate the potential of fMR imaging to assess changes in cortical representation before and after surgical intervention in patients with CSM. A future study involving a larger cohort of patients as well as the stratification of patients with CSM, based on the aforementioned factors that influence cortical adaptation, will allow a more detailed quantitative analysis.

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