scholarly journals Long-latency muscle activity reflects continuous, delayed sensorimotor feedback of task-level and not joint-level error

2013 ◽  
Vol 110 (6) ◽  
pp. 1278-1290 ◽  
Author(s):  
Seyed A. Safavynia ◽  
Lena H. Ting
Keyword(s):  
Time Course ◽  
The Body ◽  
Lower Limbs ◽  
Common Mechanism ◽  
Sensorimotor Transformation ◽  
Joint Level ◽  
Long Latency Responses ◽  
Long Latency ◽  
Sensorimotor Feedback ◽  
Task Level

In both the upper and lower limbs, evidence suggests that short-latency electromyographic (EMG) responses to mechanical perturbations are modulated based on muscle stretch or joint motion, whereas long-latency responses are modulated based on attainment of task-level goals, e.g., desired direction of limb movement. We hypothesized that long-latency responses are modulated continuously by task-level error feedback. Previously, we identified an error-based sensorimotor feedback transformation that describes the time course of EMG responses to ramp-and-hold perturbations during standing balance ( Safavynia and Ting 2013 ; Welch and Ting 2008 , 2009 ). Here, our goals were 1) to test the robustness of the sensorimotor transformation over a richer set of perturbation conditions and postural states; and 2) to explicitly test whether the sensorimotor transformation is based on task-level vs. joint-level error. We developed novel perturbation trains of acceleration pulses such that perturbations were applied when the body deviated from the desired, upright state while recovering from preceding perturbations. The entire time course of EMG responses (∼4 s) in an antagonistic muscle pair was reconstructed using a weighted sum of center of mass (CoM) kinematics preceding EMGs at long-latency delays (∼100 ms). Furthermore, CoM and joint kinematic trajectories became decorrelated during perturbation trains, allowing us to explicitly compare task-level vs. joint feedback in the same experimental condition. Reconstruction of EMGs was poorer using joint kinematics compared with CoM kinematics and required unphysiologically short (∼10 ms) delays. Thus continuous, long-latency feedback of task-level variables may be a common mechanism regulating long-latency responses in the upper and lower limbs.

scholarly journals Sensorimotor feedback based on task-relevant error robustly predicts temporal recruitment and multidirectional tuning of muscle synergies

2013 ◽  
Vol 109 (1) ◽  
pp. 31-45 ◽  
Author(s):  
Seyed A. Safavynia ◽  
Lena H. Ting
Keyword(s):  
Sagittal Plane ◽  
Balance Control ◽  
Center Of Mass ◽  
The Body ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Muscle Coordination ◽  
Initial State ◽  
Sensorimotor Feedback ◽  
Task Level

We hypothesized that motor outputs are hierarchically organized such that descending temporal commands based on desired task-level goals flexibly recruit muscle synergies that specify the spatial patterns of muscle coordination that allow the task to be achieved. According to this hypothesis, it should be possible to predict the patterns of muscle synergy recruitment based on task-level goals. We demonstrated that the temporal recruitment of muscle synergies during standing balance control was robustly predicted across multiple perturbation directions based on delayed sensorimotor feedback of center of mass (CoM) kinematics (displacement, velocity, and acceleration). The modulation of a muscle synergy's recruitment amplitude across perturbation directions was predicted by the projection of CoM kinematic variables along the preferred tuning direction(s), generating cosine tuning functions. Moreover, these findings were robust in biphasic perturbations that initially imposed a perturbation in the sagittal plane and then, before sagittal balance was recovered, perturbed the body in multiple directions. Therefore, biphasic perturbations caused the initial state of the CoM to differ from the desired state, and muscle synergy recruitment was predicted based on the error between the actual and desired upright state of the CoM. These results demonstrate that that temporal motor commands to muscle synergies reflect task-relevant error as opposed to sensory inflow. The proposed hierarchical framework may represent a common principle of motor control across motor tasks and levels of the nervous system, allowing motor intentions to be transformed into motor actions.

scholarly journals Frictional internal work of damped limbs oscillation in human locomotion

2020 ◽  
Vol 287 (1931) ◽  
pp. 20201410 ◽  
Author(s):  
Alberto E. Minetti ◽  
Alex P. Moorhead ◽  
Gaspare Pavei
Keyword(s):  
Energy Balance ◽  
Time Course ◽  
Ex Vivo ◽  
Biological Tissues ◽  
The Body ◽  
Lower Limbs ◽  
Metabolic Energy ◽  
External Work ◽  
Internal Work

Joint friction has never previously been considered in the computation of mechanical and metabolic energy balance of human and animal (loco)motion, which heretofore included just muscle work to move the body centre of mass (external work) and body segments with respect to it. This happened mainly because, having been previously measured ex vivo , friction was considered to be almost negligible. Present evidences of in vivo damping of limb oscillations, motion captured and processed by a suited mathematical model, show that: (a) the time course is exponential, suggesting a viscous friction operated by the all biological tissues involved; (b) during the swing phase, upper limbs report a friction close to one-sixth of the lower limbs; (c) when lower limbs are loaded, in an upside-down body posture allowing to investigate the hip joint subjected to compressive forces as during the stance phase, friction is much higher and load dependent; and (d) the friction of the four limbs during locomotion leads to an additional internal work that is a remarkable fraction of the mechanical external work. These unprecedented results redefine the partitioning of the energy balance of locomotion, the internal work components, muscle and transmission efficiency, and potentially readjust the mechanical paradigm of the different gaits.

Influence of stable iodine on the uptake of the thyroid – model vs. experiment

2001 ◽  
Vol 40 (01) ◽  
pp. 31-37 ◽  
Author(s):  
U. Wellner ◽  
E. Voth ◽  
H. Schicha ◽  
K. Weber
Keyword(s):  
Time Course ◽  
Compartment Model ◽  
The Body ◽  
Iodine Uptake ◽  
Model Calculations ◽  
Physiological Conditions ◽  
Iodine Supply ◽  
Predicted Values ◽  
The Individual ◽  
Stable Iodine

Summary Aim: The influence of physiological and pharmacological amounts of iodine on the uptake of radioiodine in the thyroid was examined in a 4-compartment model. This model allows equations to be derived describing the distribution of tracer iodine as a function of time. The aim of the study was to compare the predictions of the model with experimental data. Methods: Five euthyroid persons received stable iodine (200 μg, 10 mg). 1-123-uptake into the thyroid was measured with the Nal (Tl)-detector of a body counter under physiological conditions and after application of each dose of additional iodine. Actual measurements and predicted values were compared, taking into account the individual iodine supply as estimated from the thyroid uptake under physiological conditions and data from the literature. Results: Thyroid iodine uptake decreased from 80% under physiological conditions to 50% in individuals with very low iodine supply (15 μg/d) (n = 2). The uptake calculated from the model was 36%. Iodine uptake into the thyroid did not decrease in individuals with typical iodine supply, i.e. for Cologne 65-85 μg/d (n = 3). After application of 10 mg of stable iodine, uptake into the thyroid decreased in all individuals to about 5%, in accordance with the model calculations. Conclusion: Comparison of theoretical predictions with the measured values demonstrated that the model tested is well suited for describing the time course of iodine distribution and uptake within the body. It can now be used to study aspects of iodine metabolism relevant to the pharmacological administration of iodine which cannot be investigated experimentally in humans for ethical and technical reasons.

Aspergillus Spondylodiscitis After Spinal Stenosis Surgery: A Case Report

2020 ◽  
Vol 5 (3 And 4) ◽  
pp. 155-160
Author(s):  
Mohsen Aghapoor ◽  
◽  
Babak Alijani Alijani ◽  
Mahsa Pakseresht-Mogharab ◽  
◽  
...  
Keyword(s):  
Antifungal Drugs ◽  
The Body ◽  
Lower Limbs ◽  
Lumbar Pain ◽  
Case Presentation ◽  
Delay In Diagnosis ◽  
Death Case ◽  
Therapeutic Results ◽  
History Of ◽  
Probable Diagnosis

Background and Importance: Spondylodiscitis is an inflammatory disease of the body of one or more vertebrae and intervertebral disc. The fungal etiology of this disease is rare, particularly in patients without immunodeficiency. Delay in diagnosis and treatment of this disease can lead to complications and even death. Case Presentation: A 63-year-old diabetic female patient, who had a history of spinal surgery and complaining radicular lumbar pain in both lower limbs with a probable diagnosis of spondylodiscitis, underwent partial L2 and complete L3 and L4 corpectomy and fusion. As a result of pathology from tissue biopsy specimen, Aspergillus fungi were observed. There was no evidence of immunodeficiency in the patient. The patient was treated with Itraconazole 100 mg twice a day for two months. Pain, neurological symptom, and laboratory tests improved. Conclusion: The debridement surgery coupled with antifungal drugs can lead to the best therapeutic results.

Correction of Posture Deviations in the Sagittal Plane Using the Pilates Method

2019 ◽  
pp. 3-13
Author(s):  
Alexandru Cîtea ◽  
George-Sebastian Iacob
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Postural Control ◽  
Human Body ◽  
Sagittal Plane ◽  
The Body ◽  
Lower Limbs ◽  
Low Back ◽  
Pilates Method ◽  
The Relationship

Posture is commonly perceived as the relationship between the segments of the human body upright. Certain parts of the body such as the cephalic extremity, neck, torso, upper and lower limbs are involved in the final posture of the body. Musculoskeletal instabilities and reduced postural control lead to the installation of nonstructural posture deviations in all 3 anatomical planes. When we talk about the sagittal plane, it was concluded that there are 4 main types of posture deviation: hyperlordotic posture, kyphotic posture, rectitude and "sway-back" posture.Pilates method has become in the last decade a much more popular formof exercise used in rehabilitation. The Pilates method is frequently prescribed to people with low back pain due to their orientation on the stabilizing muscles of the pelvis. Pilates exercise is thus theorized to help reactivate the muscles and, by doingso, increases lumbar support, reduces pain, and improves body alignment.

scholarly journals A Feasibility Study of Kinematic Characteristics on the Upper Body According to the Shooting of Elite Disabled Archery Athletes

2021 ◽  
Vol 18 (6) ◽  
pp. 2962
Author(s):  
Tae-Whan Kim ◽  
Jae-Won Lee ◽  
Seoung-Ki Kang ◽  
Kyu-Yeon Chae ◽  
Sang-Hyup Choi ◽  
...  
Keyword(s):  
The Body ◽  
Lower Limbs ◽  
Upper Body ◽  
Movement Trajectory ◽  
Phase 2 ◽  
Kinematic Characteristics ◽  
Significant Difference ◽  
Athletes With Disabilities ◽  
Body Center ◽  
Time Required

The purpose of this study is to compare and analyze the kinematic characteristics of the upper limb segments during the archery shooting of Paralympic Wheelchair Class archers (ARW2—second wheelchair class—paraplegia or comparable disability) and Paralympic Standing Class archers (ARST—standing archery class—loss of 25 points in the upper limbs or lower limbs), where archers are classified according to their disability grade among elite disabled archers. The participants of this study were selected as seven elite athletes with disabilities by the ARW2 (n = 4) and ARST (n = 3). The analysis variables were (1) the time required for each phase, (2) the angle of inclination of the body center, (3) the change of trajectory of body center, and (4) the change of the movement trajectory of the bow center by phase when performing six shots in total. The ARW2 group (drawing phase; M = 2.228 s, p < 0.05, holding phase; M = 4.414 s, p < 0.05) showed a longer time than the ARST group (drawing phase; M = 0.985 s, holding phase; M = 3.042 s), and the angle of the body did not show a significant difference between the two groups. Additionally, in the direction of the anteroposterior axis in the drawing phase, the change in the movement trajectory of the body center showed a more significant amount of change in the ARW2 group than in the ARST group, and the change in the movement trajectory of the bow center did not show a significant difference between the two groups.

scholarly journals Involvement of Autophagy in Rat Tail Static Compression-Induced Intervertebral Disc Degeneration and Notochordal Cell Disappearance

2021 ◽  
Vol 22 (11) ◽  
pp. 5648
Author(s):  
Takashi Yurube ◽  
Hiroaki Hirata ◽  
Masaaki Ito ◽  
Yoshiki Terashima ◽  
Yuji Kakiuchi ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Disc Degeneration ◽  
Time Course ◽  
The Body ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Autophagic Flux ◽  
Static Compression ◽  
Notochordal Cell ◽  
Notochordal Cells ◽  
Rat Tail

The intervertebral disc is the largest avascular low-nutrient organ in the body. Thus, resident cells may utilize autophagy, a stress-response survival mechanism, by self-digesting and recycling damaged components. Our objective was to elucidate the involvement of autophagy in rat experimental disc degeneration. In vitro, the comparison between human and rat disc nucleus pulposus (NP) and annulus fibrosus (AF) cells found increased autophagic flux under serum deprivation rather in humans than in rats and in NP cells than in AF cells of rats (n = 6). In vivo, time-course Western blotting showed more distinct basal autophagy in rat tail disc NP tissues than in AF tissues; however, both decreased under sustained static compression (n = 24). Then, immunohistochemistry displayed abundant autophagy-related protein expression in large vacuolated disc NP notochordal cells of sham rats. Under temporary static compression (n = 18), multi-color immunofluorescence further identified rapidly decreased brachyury-positive notochordal cells with robust expression of autophagic microtubule-associated protein 1 light chain 3 (LC3) and transiently increased brachyury-negative non-notochordal cells with weaker LC3 expression. Notably, terminal deoxynucleotidyl transferase dUTP nick end labeling-positive apoptotic death was predominant in brachyury-negative non-notochordal cells. Based on the observed notochordal cell autophagy impairment and non-notochordal cell apoptosis induction under unphysiological mechanical loading, further investigation is warranted to clarify possible autophagy-induced protection against notochordal cell disappearance, the earliest sign of disc degeneration, through limiting apoptosis.

Kinematic Coordination in Human Gait: Relation to Mechanical Energy Cost

1998 ◽  
Vol 79 (4) ◽  
pp. 2155-2170 ◽  
Author(s):  
L. Bianchi ◽  
D. Angelini ◽  
G. P. Orani ◽  
F. Lacquaniti
Keyword(s):  
Energy Expenditure ◽  
Energy Cost ◽  
Time Course ◽  
Sagittal Plane ◽  
Dimensional Space ◽  
Mechanical Energy ◽  
Direction Cosine ◽  
Lower Limbs ◽  
Human Gait ◽  
Plane Orientation

Bianchi, L., D. Angelini, G. P. Orani, and F. Lacquaniti. Kinematic coordination in human gait: relation to mechanical energy cost. J. Neurophysiol. 79: 2155–2170, 1998. Twenty-four subjects walked at different, freely chosen speeds ( V) ranging from 0.4 to 2.6 m s−1, while the motion and the ground reaction forces were recorded in three-dimensional space. We considered the time course of the changes of the angles of elevation of the trunk, pelvis, thigh, shank, and foot in the sagittal plane. These angles specify the orientation of each segment with respect to the vertical and to the direction of forward progression. The changes of the trunk and pelvis angles are of limited amplitude and reflect the dynamics of both right and left lower limbs. The changes of the thigh, shank, and foot elevation are ample, and they are coupled tightly among each other. When these angles are plotted one versus the others, they describe regular loops constrained on a plane. The plane of angular covariation rotates, slightly but systematically, along the long axis of the gait loop with increasing V. The rotation, quantified by the change of the direction cosine of the normal to the plane with the thigh axis ( u 3 t ), is related to a progressive phase shift between the foot elevation and the shank elevation with increasing V. As a next step in the analysis, we computed the mass-specific mean absolute power ( P u ) to obtain a global estimate of the rate at which mechanical work is performed during the gait cycle. When plotted on logarithmic coordinates, P u increases linearly with V. The slope of this relationship varies considerably across subjects, spanning a threefold range. We found that, at any given V > 1 m s−1, the value of the plane orientation ( u 3 t ) is correlated with the corresponding value of the net mechanical power ( P u ). On the average, the progressive rotation of the plane with increasing V is associated with a reduction of the increment of P u that would occur if u 3 t remained constant at the value characteristic of low V. The specific orientation of the plane at any given speed is not the same in all subjects, but there is an orderly shift of the plane orientation that correlates with the net power expended by each subject. In general, smaller values of u 3 t tend to be associated with smaller values of P u and vice versa. We conclude that the parametric tuning of the plane of angular covariation is a reliable predictor of the mechanical energy expenditure of each subject and could be used by the nervous system for limiting the overall energy expenditure.

Loading comparison of two structures in the moving tube of a non-invasive prosthesis

2021 ◽  
pp. 1-9
Author(s):  
Jie Zhang ◽  
Ping Ye ◽  
Lizheng Zhang ◽  
Hongliu Wu ◽  
Tianxi Chi ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Normal Growth ◽  
Limb Length Discrepancy ◽  
The Body ◽  
Lower Limbs ◽  
Lower Body ◽  
Element Analysis ◽  
Non Invasive ◽  
Testing Method ◽  
Finite Element Analysis Simulation

BACKGROUND: The treatment of adolescent patients with distal femoral cancer has always been a concern. The limb-salvage, regarded as a mainstream treatment, had been developed in recent years, but its application in children still remains challenging. This is because it can lead to potential limb-length discrepancy from the continued normal growth of the contralateral lower body. The extendable prosthesis could solve this problem. The principle is that it can artificially control the length of the prosthesis, making it consistent with the length of the side of the lower limbs. However, this prosthesis has some complications. The extendable prosthesis is classified into invasive and minimally invasive, which extends the prosthesis with each operation. OBJECTIVE: We designed a new non-invasive prosthesis that can be extended in the body. Based on the non-invasive and extendable characteristics, we need to verify the supporting performance of this prosthesis. METHODS: We carried out a mechanical testing method and finite element analysis simulation. CONCLUSION: The support performance and non-invasively extension of this prosthesis were verified.

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