Reference Frames for Spinal Proprioception: Limb Endpoint Based or Joint-Level Based?

2000 ◽  
Vol 83 (5) ◽  
pp. 2931-2945 ◽  
Author(s):  
G. Bosco ◽  
R. E. Poppele ◽  
J. Eian
Keyword(s):  
Regression Model ◽  
Neuronal Activity ◽  
Reference Frames ◽  
Joint Angle ◽  
Cell Activity ◽  
Proprioceptive Information ◽  
Joint Angles ◽  
Indicator Variable ◽  
Mechanical Constraints ◽  
Foot Position

Many sensorimotor neurons in the CNS encode global parameters of limb movement and posture rather than specific muscle or joint parameters. Our investigations of spinocerebellar activity have demonstrated that these second-order spinal neurons also may encode proprioceptive information in a limb-based rather than joint-based reference frame. However, our finding that each foot position was determined by a unique combination of joint angles in the passive limb made it difficult to distinguish unequivocally between a limb-based and a joint-based representation. In this study, we decoupled foot position from limb geometry by applying mechanical constraints to individual hindlimb joints in anesthetized cats. We quantified the effect of the joint constraints on limb geometry by analyzing joint-angle covariance in the free and constrained conditions. One type of constraint, a rigid constraint of the knee angle, both changed the covariance pattern and significantly reduced the strength of joint-angle covariance. The other type, an elastic constraint of the ankle angle, changed only the covariance pattern and not its overall strength. We studied the effect of these constraints on the activity in 70 dorsal spinocerebellar tract (DSCT) neurons using a multivariate regression model, with limb axis length and orientation as predictors of neuronal activity. This model also included an experimental condition indicator variable that allowed significant intercept or slope changes in the relationships between foot position parameters and neuronal activity to be determined across conditions. The result of this analysis was that the spatial tuning of 37/70 neurons (53%) was unaffected by the constraints, suggesting that they were somehow able to signal foot position independently from the specific joint angles. We also investigated the extent to which cell activity represented individual joint angles by means of a regression model based on a linear combination of joint angles. A backward elimination of the insignificant predictors determined the set of independent joint angles that best described the neuronal activity for each experimental condition. Finally, by comparing the results of these two approaches, we could determine whether a DSCT neuron represented foot position, specific joint angles, or none of these variables consistently. We found that 10/70 neurons (14%) represented one or more specific joint-angles. The activity of another 27 neurons (39%) was significantly affected by limb geometry changes, but 33 neurons (47%) consistently elaborated a foot position representation in the coordinates of the limb axis.

Temporal features of directional tuning by spinocerebellar neurons: relation to limb geometry

1996 ◽  
Vol 75 (4) ◽  
pp. 1647-1658 ◽  
Author(s):  
G. Bosco ◽  
R. E. Poppele
Keyword(s):  
Goodness Of Fit ◽  
Sagittal Plane ◽  
Cell Activity ◽  
Local Maximum ◽  
The Other ◽  
Movement Direction ◽  
Proprioceptive Information ◽  
Joint Angles ◽  
Directional Tuning ◽  
Directional Bias

1. We showed previously that neurons in the dorsal spinocerebellar tract (DSCT) may encode whole-limb parameters of movement and posture rather than localized proprioceptive information. Neurons were found to respond to hindlimb movements in the sagittal plane with maximum activity for foot placements in one direction and minimum activity for placements in the opposite direction. In contrast, movement direction is not specifically encoded by response activity when movement are restricted to a single joint. 2. We now describe the spatiotemporal characteristics of DSCT directional sensitivity for the responses of 267 neurons to small amplitude (0.5 cm) perturbations of the cat hindlimb. A small platform attached to the left hind foot was perturbed along four or eight directions in the sagittal plane, eliciting significant responses in 261 (98%) of the cells. The responses typically consisted of a sequence of peaks and troughs in poststimulus spike density lasting 150 ms or more following limb perturbation. 3. Peaks of activity in particular poststimulus intervals were broadly tuned for the direction of the perturbation, as determined by fitting the firing rates recorded in response to each perturbation direction to a cosine model. The parameters of the cosine model, namely the amplitude of modulation, the direction of maximum response, and the goodness of fit to the model, were computed for each 4 ms poststimulus interval. The parameters all showed the same tendency to wax and wane with respect to poststimulus time. For each period during which the cell activity was highly correlated with tuning model, the tuning indicated a different best direction. Thus each cell's directional tuning could be characterized by a set of tuning maxima associated with specific poststimulus times, when the amplitude of the tuning reached a local maximum and the fit to the cosine model was highly significant (R2 > 0.85). 4. Directions of the tuning maxima for the total population of cells were not uniformly distributed within particular poststimulus intervals. There was a statistically significant directional bias for upward directed perturbations in the poststimulus interval between 20 and 40 ms, followed by a period of downward bias from 45 to 55 ms. Between 60 and 85 ms, the distribution of tuning maxima was significantly skewed backward, whereas a very strong bias for the forward direction was present at about 100 ms. 5. Because the tuning was determined from responses to a very small perturbations of the limb in a given posture, it was not clear whether the responses were related to specific joint angles or muscle lengths, or whether they somehow represented the kinematics of the whole limb. To address this point, we examined the responses of 95 cells in two animals that were each tested in two different limb positions. One position was an approximation of the normal standing position. The other position consisted of a shortening of the limb axis (with major changes in all joint angles) in one animal, or a rotation of the limb axis backward (with little change in joint angles) in the other. 6. We compared each cell's responses to the same perturbations applied in the two limb positions and found they could be identical, scaled in time or magnitude, or completely different in the two positions. A greater percentage of cells with different responses was found in the experiment with the limb axis rotated. In the other experiment, in which there were major differences in joint angles in the two positions, the responses were mostly the same or scaled in time in the two positions. We also determined the population directional biases for the two positions in each experiment, and found that phase differences between the vectors representing population biases for the two positions were minimized when they were measured relative to the orientation of the limb axis (limb coordinates) rather than to the extrinsic vertical (lab coordinates). 7.

scholarly journals Joint Angle, Range of Motion, Force, and Moment Assessment: Responses of the Lower Limb to Ankle Plantarflexion and Dorsiflexion

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Ukadike Chris Ugbolue ◽  
Chloe Robson ◽  
Emma Donald ◽  
Kerry L. Speirs ◽  
Frédéric Dutheil ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Lower Limb ◽  
Joint Angle ◽  
Joint Angles ◽  
Hip Joints ◽  
Exercise Interventions ◽  
Biomechanical Assessment ◽  
Lower Limb Exercise ◽  
Males And Females ◽  
Foot Position

There is limited research on the biomechanical assessment of the lower limb joints in relation to dynamic movements that occur at the hip, knee, and ankle joints when performing dorsiflexion (DF) and plantarflexion (PF) among males and females. This study investigated the differences in joint angles (including range of motion (ROM)) and forces (including moments) between the left and right limbs at the ankle, knee, and hip joints during dynamic DF and PF movements in both males and females. Using a general linear model employing multivariate analysis in relation to the joint angle, ROM, force, and moment datasets, the results revealed significant main effects for gender, sidedness, phases, and foot position with respect to joint angles. Weak correlations were observed between measured biomechanical variables. These results provide insightful information for clinicians and biomechanists that relate to lower limb exercise interventions and modelling efficacy standpoints.

scholarly journals Genome-Wide Association Studies Based on Equine Joint Angle Measurements Reveal New QTL Affecting the Conformation of Horses

Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 370 ◽  
Author(s):  
Annik Imogen Gmel ◽  
Thomas Druml ◽  
Rudolf von Niederhäusern ◽  
Tosso Leeb ◽  
Markus Neuditschko
Keyword(s):  
Joint Angle ◽  
Association Studies ◽  
Genome Wide Association ◽  
Cranial Morphology ◽  
Genome Wide Association Studies ◽  
Joint Angles ◽  
Mineral Density ◽  
Mixed Effect ◽  
Stifle Joint ◽  
Genome Wide

The evaluation of conformation traits is an important part of selection for breeding stallions and mares. Some of these judged conformation traits involve joint angles that are associated with performance, health, and longevity. To improve our understanding of the genetic background of joint angles in horses, we have objectively measured the angles of the poll, elbow, carpal, fetlock (front and hind), hip, stifle, and hock joints based on one photograph of each of the 300 Franches-Montagnes (FM) and 224 Lipizzan (LIP) horses. After quality control, genome-wide association studies (GWASs) for these traits were performed on 495 horses, using 374,070 genome-wide single nucleotide polymorphisms (SNPs) in a mixed-effect model. We identified two significant quantitative trait loci (QTL) for the poll angle on ECA28 (p = 1.36 × 10−7), 50 kb downstream of the ALX1 gene, involved in cranial morphology, and for the elbow joint on ECA29 (p = 1.69 × 10−7), 49 kb downstream of the RSU1 gene, and 75 kb upstream of the PTER gene. Both genes are associated with bone mineral density in humans. Furthermore, we identified other suggestive QTL associated with the stifle joint on ECA8 (p = 3.10 × 10−7); the poll on ECA1 (p = 6.83 × 10−7); the fetlock joint of the hind limb on ECA27 (p = 5.42 × 10−7); and the carpal joint angle on ECA3 (p = 6.24 × 10−7), ECA4 (p = 6.07 × 10−7), and ECA7 (p = 8.83 × 10−7). The application of angular measurements in genetic studies may increase our understanding of the underlying genetic effects of important traits in equine breeding.

scholarly journals Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2690
Author(s):  
Bo Pan ◽  
Xuguang Wang ◽  
Zhenyang Xu ◽  
Lianjun Guo ◽  
Xuesong Wang
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Joint Angle ◽  
Simulation Software ◽  
Dissipated Energy ◽  
Energy Structure ◽  
Joint Angles ◽  
Crack Penetration ◽  
Before And After ◽  
The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

Gyroscope-Free Link Parameter Measurement Using Accelerometers and Magnetometer

2014 ◽  
Author(s):  
Vishesh Vikas ◽  
Carl D. Crane
Keyword(s):  
Angular Velocity ◽  
Joint Angle ◽  
Inertial Sensors ◽  
Angular Acceleration ◽  
Parameter Measurement ◽  
Joint Angles ◽  
Symmetry Constraint ◽  
Estimation Techniques ◽  
Angular Velocities ◽  
Joint Parameters

Knowledge of joint angles, angular velocities is essential for control of link mechanisms and robots. The estimation of joint angles and angular velocity is performed using combination of inertial sensors (accelerometers and gyroscopes) which are contactless and flexible at point of application. Different estimation techniques are used to fuse data from different inertial sensors. Bio-inspired sensors using symmetrically placed multiple inertial sensors are capable of instantaneously measuring joint parameters (joint angle, angular velocities and angular acceleration) without use of any estimation techniques. Calibration of inertial sensors is easier and more reliable for accelerometers as compared to gyroscopes. The research presents gyroscope-less, multiple accelerometer and magnetometer based sensors capable of measuring (not estimating) joint parameters. The contribution of the improved sensor are four-fold. Firstly, the inertial sensors are devoid of symmetry constraint unlike the previously researched bio-inspired sensors. However, the accelerometer are non-coplanarly placed. Secondly, the accelerometer-magnetometer combination sensor allows for calculation of a unique rotation matrix between two link joined by any kind of joint. Thirdly, the sensors are easier to calibrate as they consist only of accelerometers. Finally, the sensors allow for calculation of angular velocity and angular acceleration without use of gyroscopes.

scholarly journals A Workspace Visualization Method for a Multijoint Industrial Robot Based on the 3D-Printing Layering Concept

2020 ◽  
Vol 10 (15) ◽  
pp. 5241
Author(s):  
Guoqiang Fu ◽  
Chun Tao ◽  
Tengda Gu ◽  
Caijiang Lu ◽  
Hongli Gao ◽  
...  
Keyword(s):  
3D Printing ◽  
Joint Angle ◽  
Industrial Robot ◽  
Selection Method ◽  
Forward Kinematics ◽  
Visualization Method ◽  
Joint Angles ◽  
Boundary Extraction ◽  
Simulation And Experiment ◽  
Constraint Information

The workspace of a robot provides the necessary constraint information for path planning and reliable control of the robot. In this paper, a workspace visualization method for a multijoint industrial robot is proposed to obtain a detailed workspace by introducing the 3D-printing layering concept. Firstly, all possible joint-angle groups of one pose in the joints’ ranges are calculated in detail according to the POE (product of exponential) theory-based forward-kinematics expressions of the multijoint industrial robot. Secondly, a multisolution selection method based on the key degree of the joint is proposed to select the appropriate joint-angle groups. The key degrees of all joints and their key order are obtained according to the sensitivity expressions of all joint angles, calculated from the Jacobian matrix of the robot. One principle based on the smallest differences of the nominal angle is established to select the possible solutions for one joint from the possible solutions for the joint with the smaller key order. The possible solutions for the joint with the highest key order are the appropriate joint-angle group. Thirdly, a workspace visualization method based on the layering concept of 3D printing is presented to obtain a detailed workspace for a multijoint industrial robot. The boundary formula of each layer is derived by forward kinematics, which is expressed as a circle or a ring. The maximum and minimum values of the radius are obtained according to the travel range of the joint angles. The height limitations of all layers are obtained with forward kinematics. A workspace boundary-extraction method is presented to obtain the array of path points of the boundary at each layer. The proposed postprocessing method is used to generate the joint-angle code of each layer for direct 3D printing. Finally, the effectiveness of the multisolution selection method and the workspace visualization method were verified by simulation and experiment.

scholarly journals Can foot angle influence the risk of injury to the lower limb joints during a field hockey hit?

2019 ◽  
Vol 5 (1) ◽  
pp. e000568
Author(s):  
Frances E Feeley ◽  
Graham P Arnold ◽  
Sadiq Nasir ◽  
Weijie W Wang ◽  
Rami Abboud
Keyword(s):  
Lower Limb ◽  
Injury Risk ◽  
Knee Injury ◽  
Body Part ◽  
Ankle Sprains ◽  
Field Hockey ◽  
Joint Angles ◽  
Lateral Ankle ◽  
Risk Of Injury ◽  
Foot Position

ObjectivesThe lower limb is widely reported as the most commonly injured body part in the field of hockey, more specifically lateral ankle sprains and internal knee injury. Despite this, there remains limited understanding of how the biomechanics of the sport could be adapted to minimise injury. The aim of this study was to propose a foot position during the hockey hit that results in the smallest joint angles and moments, from a total of four different foot positions: 0°, 30°, 60° and 90°, which may correlate to injury risk.MethodEighteen players from the local University Ladies Hockey Club participated in this study. Each player was required to perform a hit with their lead foot in four different positions: 0°, 30°, 60° and 90°, where 0° was a lead foot position perpendicular to the direction of motion of the ball. Angles and moments were calculated with the Vicon system using force plates and motion analysis.ResultsSignificant differences (p<0.05) were found between the angles and moments of the four foot positions tested, indicating that foot angle can influence the degree of angulation, and moments, produced in the lower limb joints during the hockey hit.ConclusionThere is a relationship between lead foot position and the angles and moments produced in the lower limb joints during the hockey hit, and this may correlate with injury risk.

scholarly journals Estimation of Continuous Joint Angles of Upper Limb Based on sEMG by Using GA-Elman Neural Network

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Junhong Wang ◽  
Qiqi Hao ◽  
Xugang Xi ◽  
Jiuwen Cao ◽  
Anke Xue ◽  
...  
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Elbow Joint ◽  
Joint Angle ◽  
Wavelet Packet ◽  
Upper Limbs ◽  
Joint Angles ◽  
Semg Signal ◽  
Elman Neural Network ◽  
Shoulder Movement

The estimation of continuous and simultaneous multijoint angle based on surface electromyography (sEMG) signal is of considerable significance in rehabilitation practice. However, there are few studies on the continuous joint angle of multiple joints at present. In this paper, the wavelet packet energy entropy (WPEE) of the special subspace was investigated as a feature of the sEMG signal. An Elman neural network optimized by genetic algorithm (GA) was established to estimate the joint angle of shoulder and elbow. First, the accuracy of the method is verified by estimating the angle of the shoulder joint. Then, this method was used to simultaneously and continuously estimate the shoulder and elbow joint angle. Six subjects flexed and extended the upper limbs according to the intended movements of the experiment. The results show that this method can obtain a decent performance with a RMSE of 3.4717 and R2 of 0.8283 in shoulder movement and with a RMSE of 4.1582 and R2 of 0.8114 in continuous synchronous movement of the shoulder and elbow.

Responses of medullary raphespinal neurons to electrical stimulation of thoracic sympathetic afferents, vagal afferents, and to other sensory inputs in cats

1991 ◽  
Vol 66 (6) ◽  
pp. 2084-2094 ◽  
Author(s):  
R. W. Blair ◽  
A. R. Evans
Keyword(s):  
Electrical Stimulation ◽  
Neuronal Activity ◽  
Vagal Stimulation ◽  
Discharge Rate ◽  
Stellate Ganglion ◽  
Cell Activity ◽  
Conditioning Stimulus ◽  
Vagal Afferents ◽  
Early Peak ◽  
Stimulation Of

1. Medullary raphespinal neurons antidromically activated from the T2-T5 segments were tested for responses to electrical stimulation of cervical vagal and thoracic sympathetic afferents (by stimulating the left stellate ganglion), somatic probing, auditory stimuli, and visual stimuli in cats anesthetized with alpha-chloralose. A total of 99 neurons in the raphe nuclei were studied; the locations of 76 cells were histologically confirmed. Neurons were located in raphe magnus (RM, 65%), raphe obscurus (RO, 32%), and raphe pallidus (RPa, 4%). The mean conduction velocity of these neurons was 62 +/- 2.9 (SE) m/s with a range of 1.1-121 m/s. 2. A total of 60/99 tested neurons responded to electrical stimulation of sympathetic afferents. Quantitation of responses was obtained for 55 neurons. With one exception, all responsive neurons were excited and exhibited an early burst of spikes with a mean latency of 16 +/- 1.2 ms. From a spontaneous discharge rate of 5.2 +/- 1.2 spikes/s, neuronal activity increased by 2.9 +/- 0.3 spikes/stimulus. In addition to an early peak, 15 neurons (25%) exhibited a late burst of spikes with a latency of 182 +/- 12.9 ms; neuronal activity increased by 5.0 +/- 1.3 spikes/stimulus. Duration of the late peak (130 +/- 18.5 ms) was longer than for the early peak (18 +/- 0.7 ms), but threshold voltages for eliciting each peak were comparable. Sixteen of 29 spontaneously active neurons exhibited a postexcitatory depression of activity that lasted for 163 +/- 19.1 ms. All but one tested neuron in RO responded to stimulation of sympathetic afferents, but 65% of neurons in RM responded to this stimulus. 3. In response to vagal afferent stimulation, 19% of 57 neurons exhibited inhibition only, 11% were only excited, and 9% were either excited or inhibited, depending on the stimulus paradigm used; the remaining 61% of neurons were unresponsive. From a spontaneous rate of 7.9 +/- 3.8 spikes/s, excited cells increased their discharge rate by 1.6 +/- 0.3 spikes/stimulus. Activity of inhibited cells was reduced from 21.3 +/- 5.8 to 7.8 +/- 3.1 spikes/s. The conditioning-test (CT) technique was used to assess 11 neurons' responses. Stellate ganglion stimulation was the test stimulus, and vagal stimulation the conditioning stimulus. Vagal stimulation reduced the neuronal responses to stellate ganglion stimulation by an average of 50% with a CT interval of 60-100 ms, and cell responses returned to control after 300 ms. With spontaneous cell activity, low frequencies of vagal stimulation were generally excitatory, and high frequencies (10-20 Hz) inhibitory.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Kinematic-based locomotion mode recognition for power augmentation exoskeleton

2017 ◽  
Vol 14 (5) ◽  
pp. 172988141773032 ◽  
Author(s):  
Hongchul Kim ◽  
Young June Shin ◽  
Jung Kim
Keyword(s):  
Joint Angle ◽  
Identification Accuracy ◽  
Sensor Data ◽  
Knee Joint Angle ◽  
Stair Ascent ◽  
Mode Recognition ◽  
Different Types ◽  
Locomotion Mode ◽  
The Difference ◽  
Foot Position

This article presents a kinematic-based method for locomotion mode recognition, for use in the control of an exoskeleton for power augmentation, to implement natural and smooth locomotion transition. The difference in vertical foot position between a foot already in contact with ground and a foot newly in contact with the ground was calculated via kinematics for the entire exoskeleton and used to identify the locomotion mode with other sensor data including data on the knee joint angle and inclination of the thigh, shank, and foot. Locomotion on five different types of terrain—level-ground walking, stair ascent, stair descent, ramp ascent, and ramp descent—were identified using two-layer decision tree classes. An updating process is proposed to improve identification of the transition and accuracy using the foot inclination at the mid-stance. An average identification accuracy of more than 99% was achieved in experiments with eight subjects for single terrains (no terrain transitions) and hybrid terrains. The experimental results show that the proposed method can achieve high accuracy without significant misrecognition and minimize the delay in locomotion mode recognition of the exoskeleton.

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