scholarly journals The primary afferent activity cannot capture the dynamical features of muscle activity during reaching movements

2017 ◽  
Author(s):  
Russell L. Hardesty ◽  
Matthew T. Boots ◽  
Sergiy Yakovenko ◽  
Valeriya Gritsenko
Keyword(s):  
Muscle Activity ◽  
Sensory Feedback ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Afferent Feedback ◽  
Reaching Movements ◽  
Afferent Activity ◽  
Primary Afferent ◽  
Limb Dynamics ◽  
Dynamical Features

AbstractThe stabilizing role of sensory feedback in relation to realistic 3-dimensional movement dynamics remains poorly understood. The objective of this study was to quantify how primary afferent activity contributes to shaping muscle activity patterns during reaching movements. To achieve this objective, we designed a virtual reality task that guided healthy human subjects through a set of planar reaching movements with controlled kinematic and dynamic conditions that minimized inter-subject variability. Next, we integrated human upper-limb models of musculoskeletal dynamics and proprioception to analyze motion and major muscle activation patterns during these tasks. We recorded electromyographic and motion-capture data and used the integrated model to simulate joint kinematics, joint torques due to muscle contractions, muscle length changes, and simulated primary afferent feedback. The parameters of the primary afferent model were altered systematically to evaluate the effect of fusimotor drive. The experimental and simulated data were analyzed with hierarchical clustering. We found that the muscle activity patterns contained flexible task-dependent groups that consisted of co-activating agonistic and antagonistic muscles that changed with the dynamics of the task. The activity of muscles spanning only the shoulder generally grouped into a proximal cluster, while the muscles spanning the wrist grouped into a distal cluster. The bifunctional muscle spanning the shoulder and elbow were flexibly grouped with either proximal or distal cluster based on the dynamical requirements of the task. The composition and activation of these groups reflected the relative contribution of active and passive forces to each motion. In contrast, the simulated primary afferent feedback was most related to joint kinematics rather than dynamics, even though the primary afferent models had nonlinear dynamical components and variable fusimotor drive. Simulated physiological changes to the fusimotor drive were not sufficient to reproduce the dynamical features in muscle activity pattern. Altogether, these results suggest that sensory feedback signals are in a different domain from that of muscle activation signals. This indicates that to solve the neuromechanical problem, the central nervous system controls limb dynamics through task-dependent co-activation of muscles and non-linear modulation of monosynaptic primary afferent feedback.New & NoteworthyHere we answered the fundamental question in sensorimotor transformation of how primary afferent signals can contribute to the compensation for limb dynamics evident in muscle activity. We combined computational and experimental approaches to create a new experimental paradigm that challenges the nervous system with passive limb dynamics that either assists or resists the desired movement. We found that the active dynamical features present in muscle activity are unlikely to arise from direct feedback from primary afferents.

Muscle Activity as a Releasing Factor for Pain in the Shoulder and Neck

Cephalalgia ◽  
1999 ◽  
Vol 19 (25_suppl) ◽  
pp. 1-8 ◽  
Author(s):  
RH Westgaard
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Experimental Situation ◽  
Activity Patterns ◽  
Trapezius Muscle ◽  
Emg Activity ◽  
Occupational Setting ◽  
Autonomic Activation ◽  
Pain Symptoms ◽  
Vocational Studies

In this review, the evidence for trapezius muscle activity as a releasing factor for shoulder and neck pain is considered, mainly on the basis of studies in our laboratory. Two lines of evidence are produced, (i) vocational studies in an occupational setting, where muscle activity pattern is recorded by surface EMG and a clinical examination of the shoulder region of the subjects performed; and (ii) laboratory studies where muscle activity patterns and pain development are recorded in an experimental situation with mental stress and minimal physical activity. The vocational studies demonstrate pain development in the shoulder and neck despite very low muscle activity recorded, making it very difficult to assume muscular involvement for all cases with such complaints. However, the hypothesis of pain development through overexertion of a subpopulation of low-threshold motor units also makes it difficult to draw a firm negative conclusion. The laboratory experiments, on the other hand, show that trapezius activity patterns in response to stress have many features that would be expected if muscle activation induces pain symptoms. It is further noted that the trapezius is the only muscle with activity patterns that show these features. Possibly, we observe the effects of parallel physiological phenomena, e.g., a systemic autonomic activation that induces pain symptoms and also facilitates the motor response of some muscles. Evidence of autonomic activation of trapezius is presented by the observation of low-level, rhythmic EMG activity during sleep. However, this is not firm evidence for the above hypothesis, which at present best serves as a basis for further experimentation.

scholarly journals Role of muscle spindle feedback in regulating muscle activity strength during walking at different speed in mice

2018 ◽  
Vol 120 (5) ◽  
pp. 2484-2497 ◽  
Author(s):  
William P. Mayer ◽  
Andrew J. Murray ◽  
Susan Brenner-Morton ◽  
Thomas M. Jessell ◽  
Warren G. Tourtellotte ◽  
...  
Keyword(s):  
Muscle Spindle ◽  
Amplitude Modulation ◽  
Muscle Activity ◽  
Sensory Feedback ◽  
Walking Speed ◽  
Muscle Spindles ◽  
Afferent Feedback ◽  
Triceps Surae ◽  
Extensor Muscles

Terrestrial animals increase their walking speed by increasing the activity of the extensor muscles. However, the mechanism underlying how this speed-dependent amplitude modulation is achieved remains obscure. Previous studies have shown that group Ib afferent feedback from Golgi tendon organs that signal force is one of the major regulators of the strength of muscle activity during walking in cats and humans. In contrast, the contribution of group Ia/II afferent feedback from muscle spindle stretch receptors that signal angular displacement of leg joints is unclear. Some studies indicate that group II afferent feedback may be important for amplitude regulation in humans, but the role of muscle spindle feedback in regulation of muscle activity strength in quadrupedal animals is very poorly understood. To examine the role of feedback from muscle spindles, we combined in vivo electrophysiology and motion analysis with mouse genetics and gene delivery with adeno-associated virus. We provide evidence that proprioceptive sensory feedback from muscle spindles is important for the regulation of the muscle activity strength and speed-dependent amplitude modulation. Furthermore, our data suggest that feedback from the muscle spindles of the ankle extensor muscles, the triceps surae, is the main source for this mechanism. In contrast, muscle spindle feedback from the knee extensor muscles, the quadriceps femoris, has no influence on speed-dependent amplitude modulation. We provide evidence that proprioceptive feedback from ankle extensor muscles is critical for regulating muscle activity strength as gait speed increases. NEW & NOTEWORTHY Animals upregulate the activity of extensor muscles to increase their walking speed, but the mechanism behind this is not known. We show that this speed-dependent amplitude modulation requires proprioceptive sensory feedback from muscle spindles of ankle extensor muscle. In the absence of muscle spindle feedback, animals cannot walk at higher speeds as they can when muscle spindle feedback is present.

scholarly journals The primary motor cortex prospectively computes the spinal reflex

2020 ◽  
Author(s):  
Tatsuya Umeda ◽  
Tadashi Isa ◽  
Yukio Nishimura
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Linear Models ◽  
Movement Control ◽  
Spinal Reflex ◽  
Afferent Activity ◽  
Precise Movement ◽  
Behaving Monkeys

AbstractThe spinal reflex transforms sensory signals to generate muscle activity. However, it is unknown how the motor cortex (MCx) takes the spinal reflex into account when performing voluntary limb movements. We simultaneously recorded the activity of the MCx, afferent neurons, and forelimb muscles in behaving monkeys. We decomposed muscle activity into subcomponents explained by the MCx or afferent activity using linear models. Long preceding activity in the MCx, which is responsible for subsequent afferent activity, had the same spatiotemporal contribution to muscle activity as afferent activity, indicating that the MCx drives muscle activity not only by direct descending activation but also by trans-afferent descending activation. Therefore, the MCx implements internal models that prospectively estimate muscle activation via the spinal reflex for precise movement control.

scholarly journals Vision fine-tunes preparation for landing in the cane toad, Rhinella marina

2018 ◽  
Vol 14 (9) ◽  
pp. 20180397 ◽  
Author(s):  
Laura J. Ekstrom ◽  
Chris Panzini ◽  
Gary B. Gillis
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Fine Tuning ◽  
Emg Activity ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Impact Forces ◽  
Before And After ◽  
The Impact

In toad hopping, the hindlimbs generate the propulsive force for take-off while the forelimbs resist the impact forces associated with landing. Preparing to perform a safe landing, in which impact forces are managed appropriately, likely involves the integration of multiple types of sensory feedback. In toads, vestibular and/or proprioceptive feedback is critical for coordinated landing; however, the role of vision remains unclear. To clarify this, we compare pre-landing forelimb muscle activation patterns before and after removing vision. Specifically, we recorded EMG activity from two antagonistic forelimb muscles, the anconeus and coracoradialis, which demonstrate distance-dependent onset timing and recruitment intensity, respectively. Toads were first recorded hopping normally and then again after their optic nerves were severed to remove visual feedback. When blind, toads exhibited hop kinematics and pre-landing muscle activity similar to when sighted. However, distance-dependent relationships for muscle activity patterns were more variable, if present at all. This study demonstrates that blind toads are still able to perform coordinated landings, reinforcing the importance of proprioceptive and/or vestibular feedback during hopping. But the increased variability in distance-dependent activity patterns indicates that vision is more responsible for fine-tuning the motor control strategy for landing.

Simulation of Movement in Three-Dimensional Musculoskeletal Human Lumbar Spine Using Directional Encoding-Based Neurocontrollers

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Bahman Nasseroleslami ◽  
Gholamreza Vossoughi ◽  
Mehrdad Boroushaki ◽  
Mohamad Parnianpour
Keyword(s):  
Lumbar Spine ◽  
Musculoskeletal System ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Sensory Information ◽  
Model Parameters ◽  
Directional Information ◽  
Muscle Activation Patterns ◽  
Human Lumbar Spine

Despite development of accurate musculoskeletal models for human lumbar spine, the methods for prediction of muscle activity patterns in movements lack proper association with corresponding sensorimotor integrations. This paper uses the directional information of the Jacobian of the musculoskeletal system to orchestrate adaptive critic-based fuzzy neural controller modules for controlling a complex nonlinear redundant musculoskeletal system. The proposed controller is used to control a 3D 3-degree of freedom (DOF) musculoskeletal model of trunk, actuated by 18 muscles. The controller is capable of learning to control from sensory information, without relying on pre-assumed model parameters. Simulation results show satisfactory tracking of movements and the simulated muscle activation patterns conform to previous EMG experiments and optimization studies. The proposed controller can be used as a computationally inexpensive muscle activity generator to distinguish between neural and mechanical contributions to movement and for study of sensory versus motor origins of motor function and dysfunction in human spine.

Transfer of postural adaptation depends on context of prior exposure

2014 ◽  
Vol 111 (7) ◽  
pp. 1466-1478 ◽  
Author(s):  
Alison Pienciak-Siewert ◽  
Anthony J. Barletta ◽  
Alaa A. Ahmed
Keyword(s):  
Postural Control ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Center Of Pressure ◽  
Dynamic Environment ◽  
The Other ◽  
Reaching Movements ◽  
Robotic Arm ◽  
Anticipatory Postural Control ◽  
Base Of Support

Postural control is significantly affected by the postural base of support; however, the effects on postural adaptation are not well understood. Here we investigated how adaptation and transfer of anticipatory postural control are affected by stance width. Subjects made reaching movements in a novel dynamic environment while holding the handle of a force-generating robotic arm. Each subject initially adapted to the dynamics while standing in a wide stance and then switched to a narrow stance, or vice versa. Our hypothesis is that anticipatory postural control, reflected in center of pressure (COP) movement, is not affected by stance width, as long as the control remains within functional limits; therefore we predicted that subjects in either stance would show similar COP movement by the end of adaptation and immediately upon transfer to the other stance. We found that both groups showed similar adaptation of postural control, by using different muscle activation strategies to account for the differing stance widths. One group, after adapting in wide stance, transferred similar postural control to narrow stance, by modifying their muscle activity to account for the new stance. Interestingly, the other group showed an increase in postural control when transferring from narrow to wide stance, associated with no change in muscle activity. These results confirm that adaptation of anticipatory postural control is not affected by stance width, as long as the control remains within biomechanical limits. However, transfer of control between stance widths is affected by the initial context in which the task is learned.

scholarly journals An In Vitro Spinal Cord–Hindlimb Preparation for Studying Behaviorally Relevant Rat Locomotor Function

2009 ◽  
Vol 101 (2) ◽  
pp. 1114-1122 ◽  
Author(s):  
Heather Brant Hayes ◽  
Young-Hui Chang ◽  
Shawn Hochman
Keyword(s):  
Spinal Cord ◽  
Sensory Feedback ◽  
Muscle Activation ◽  
Motor Pattern ◽  
Motor Output ◽  
Afferent Feedback ◽  
Neonatal Rat ◽  
Stride Frequency ◽  
Muscle Activation Patterns

Although the spinal cord contains the pattern-generating circuitry for producing locomotion, sensory feedback reinforces and refines the spatiotemporal features of motor output to match environmental demands. In vitro preparations, such as the isolated rodent spinal cord, offer many advantages for investigating locomotor circuitry, but they lack the natural afferent feedback provided by ongoing locomotor movements. We developed a novel preparation consisting of an isolated in vitro neonatal rat spinal cord oriented dorsal-up with intact hindlimbs free to step on a custom-built treadmill. This preparation combines the neural accessibility of in vitro preparations with the modulatory influence of sensory feedback from physiological hindlimb movement. Locomotion induced by N-methyl d-aspartate and serotonin showed kinematics similar to that of normal adult rat locomotion. Changing orientation and ground interaction (dorsal-up locomotion vs ventral-up air-stepping) resulted in significant kinematic and electromyographic changes that were comparable to those reported under similar mechanical conditions in vivo. We then used two mechanosensory perturbations to demonstrate the influence of sensory feedback on in vitro motor output patterns. First, swing assistive forces induced more regular, robust muscle activation patterns. Second, altering treadmill speed induced corresponding changes in stride frequency, confirming that changes in sensory feedback can alter stride timing in vitro. In summary, intact hindlimbs in vitro can generate behaviorally appropriate locomotor kinematics and responses to sensory perturbations. Future studies combining the neural and chemical accessibility of the in vitro spinal cord with the influence of behaviorally appropriate hindlimb movements will provide further insight into the operation of spinal motor pattern-generating circuits.

scholarly journals Contribution of sensory feedback to plantar flexor muscle activation during push-off in adults with cerebral palsy

2017 ◽  
Vol 118 (6) ◽  
pp. 3165-3174 ◽  
Author(s):  
Rasmus F. Frisk ◽  
Peter Jensen ◽  
Henrik Kirk ◽  
Laurent J. Bouyer ◽  
Jakob Lorentzen ◽  
...  
Keyword(s):  
Cerebral Palsy ◽  
Ankle Joint ◽  
Muscle Activity ◽  
Sensory Feedback ◽  
Muscle Activation ◽  
Gait Training ◽  
Plantar Flexor ◽  
Passive Stiffness ◽  
Flexor Muscle ◽  
Sensory Activity

Exaggerated sensory activity has been assumed to contribute to functional impairment following lesion of the central motor pathway. However, recent studies have suggested that sensory contribution to muscle activity during gait is reduced in stroke patients and children with cerebral palsy (CP). We investigated whether this also occurs in CP adults and whether daily treadmill training is accompanied by alterations in sensory contribution to muscle activity. Seventeen adults with CP and 12 uninjured individuals participated. The participants walked on a treadmill while a robotized ankle-foot orthosis applied unload perturbations at the ankle, thereby removing sensory feedback naturally activated during push-off. Reduction of electromyographic (EMG) activity in the soleus muscle caused by unloads was compared and related to kinematics and ankle joint stiffness measurements. Similar measures were obtained after 6 wk of gait training. We found that sensory contribution to soleus EMG activation was reduced in CP adults compared with uninjured adults. The lowest contribution of sensory feedback was found in participants with lowest maximal gait speed. This was related to increased ankle plantar flexor stiffness. Six weeks of gait training did not alter the contribution of sensory feedback. We conclude that exaggerated sensory activity is unlikely to contribute to impaired gait in CP adults, because sensory contribution to muscle activity during gait was reduced compared with in uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait so that a larger part of plantar flexor muscle activity must be generated by descending motor commands.NEW & NOTEWORTHY Findings suggest that adults with cerebral palsy have less contribution of sensory feedback to ongoing soleus muscle activation during push-off than uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait, and/or sensory feedback is less integrated with central motor commands in the activation of spinal motor neurons. Consequently, muscle activation must to a larger extent rely on descending drive, which is already decreased because of the cerebral lesion.

More than a footwedge: Golf-specific footwear alters muscle activation patterns during standing balance

2020 ◽  
pp. 175433712093826
Author(s):  
Samuel J Wilson ◽  
Jacob R Gdovin ◽  
Charles C Williams ◽  
Paul T Donahue ◽  
James G Mouser ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Standing Balance ◽  
Medial Gastrocnemius ◽  
Extrinsic Factors ◽  
Activation Patterns ◽  
Intrinsic Factors ◽  
Muscle Activation Patterns

Within a golf swing, one aspect that stands out in each phase is the ability to maintain balance. Previous reports suggest that extrinsic factors, such as footwear, and intrinsic factors, such as muscular exertion level, have detrimental effects on human postural control. However, no studies have examined the effects of modern golf footwear on muscle activity of the lower extremity. Thus, the purpose of this study was to examine differences in muscle activity when walking for extended durations in golf footwear. Participants were tested for balance prior to walking sessions and then every 60 min until the 240th minute in three types of golf footwear; dress shoes, tennis shoes, and casual shoes, and barefoot. Mean muscle activity during balance testing of the vastus medialis, semitendinosus, tibialis anterior, and medial gastrocnemius was examined using a 4 × 5 repeated measures analysis of variance to identify differences within time and footwear types. Increases in muscle activity were observed after the second hour. Footwear differences were observed in the dress shoe and tennis shoe style relative to the casual style, and primarily attributed to the increased sole/midsole thickness, and increased mass of the dress shoe. These results suggest that golf footwear characteristics may alter muscle activity patterns during standing balance.

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