Clonus is explained from increased reflex gain and enlarged tissue viscoelasticity

Vlugt, Erwin de; Groot, Jurriaan H. de; Wisman, Wessel; Meskers, Carel G.M.

doi:10.1016/j.jbiomech.2011.09.023

Cited by 16 publications

(25 citation statements)

References 27 publications

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“…However, this is further qualified by interacting and interconnected pools of the spinal cord interneurons, proprioceptive feedback information from muscle spindles/Golgi-tendon organs, and modulation from higher neural centers all the way to the motor cortex of the brain. It is vital for any model to capture this closed loop nature of the neuromuscular system, as clinically observed pathologies may only be fully explained in the context of feedback dynamics [2], [5], [6]. Note that here we refer not only to the feedback from the skeletal muscles, but also the intra-spinal loops that serve to coordinate and modulate reflexes as well as other complex behaviors.…”

Section: Disciplines Disciplinesmentioning

confidence: 99%

Modeling and Identification of a Realistic Spiking Neural Network and Musculoskeletal Model of the Human Arm, and an Application to the Stretch Reflex

Sreenivasa¹,

Ayusawa

Nakamura

2016

IEEE Trans. Neural Syst. Rehabil. Eng.

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This study develops a multi-level neuromuscular model consisting of topological pools of spiking motor, sensory and interneurons controlling a bi-muscular model of the human arm. The spiking output of motor neuron pools were used to drive muscle actions and skeletal movement via neuromuscular junctions. Feedback information from muscle spindles were relayed via monosynaptic excitatory and disynaptic inhibitory connections, to simulate spinal afferent pathways. Subject-specific model parameters were identified from human experiments by using inverse dynamics computations and optimization methods. The identified neuromuscular model was used to simulate the biceps stretch reflex and the results were compared to an independent dataset. The proposed model was able to track the recorded data and produce dynamically consistent neural spiking patterns, muscle forces and movement kinematics under varying conditions of external forces and co-contraction levels. This additional layer of detail in neuromuscular models has important relevance to the research communities of rehabilitation and clinical movement analysis by providing a mathematical approach to studying neuromuscular pathology.

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Section: Disciplines Disciplinesmentioning

confidence: 99%

Modeling and Identification of a Realistic Spiking Neural Network and Musculoskeletal Model of the Human Arm, and an Application to the Stretch Reflex

Sreenivasa¹,

Ayusawa

Nakamura

2016

IEEE Trans. Neural Syst. Rehabil. Eng.

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“…For example, increases in muscle stiffness and changes in the joint angles that produce optimal torque may contribute to the decreased threshold and increased gain of the stretch reflex pathway that mediate, in part, the oscillatory activation of muscles during clonus (de Vlugt et al, 2012). …”

Section: Changes In Tissue Properties After Scimentioning

confidence: 99%

Recovery of neuronal and network excitability after spinal cord injury and implications for spasticity

D’Amico

Condliffe

Martins

et al. 2014

Front. Integr. Neurosci.

104

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The state of areflexia and muscle weakness that immediately follows a spinal cord injury (SCI) is gradually replaced by the recovery of neuronal and network excitability, leading to both improvements in residual motor function and the development of spasticity. In this review we summarize recent animal and human studies that describe how motoneurons and their activation by sensory pathways become hyperexcitable to compensate for the reduction of functional activation of the spinal cord and the eventual impact on the muscle. Specifically, decreases in the inhibitory control of sensory transmission and increases in intrinsic motoneuron excitability are described. We present the idea that replacing lost patterned activation of the spinal cord by activating synaptic inputs via assisted movements, pharmacology or electrical stimulation may help to recover lost spinal inhibition. This may lead to a reduction of uncontrolled activation of the spinal cord and thus, improve its controlled activation by synaptic inputs to ultimately normalize circuit function. Increasing the excitation of the spinal cord with spared descending and/or peripheral inputs by facilitating movement, instead of suppressing it pharmacologically, may provide the best avenue to improve residual motor function and manage spasticity after SCI.

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“…Normalization is based on the maximum muscle activation achieved if all MNs are firing at their tetanic frequency. This activation signal was used as input to Hill-type muscle models [11] used to represent the viscoelastic and contractile behavior of the musculotendon unit of each muscle encompassing the model of the Triceps Surae ( TS). Musculotendon lengths and moment arms were estimated from inverse dynamics data from humans depending on the ankle joint angle rotating in the sagittal plane [12].…”

Section: B Neuromusculoskeletal Modelmentioning

confidence: 99%

Low-frequency fluctuations of plantar flexion torque in force and position control tasks studied experimentally and by a neuromusculoskeletal model

Watanabe

Elias

Kohn

2013

2013 6th International IEEE/EMBS Conference on Neural Engineering (NER)

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There are many feedback loops potentially active while a subject performs a plantar flexion. One of these loops encompasses the proprioceptive feedback from muscle spindle Ia afferents, motor neurons (MNs), and the muscle. The aim of this study was to investigate the role of the Ia feedback loop on the low-frequency fluctuations of the plantar flexion torque during the performance of a force task (FT) and a position task (PT). Experiments were conducted on healthy human subjects and provided reference data for computer simulations that were carried out on a biologically-based largescale neuromusculoskeletal model. Spectral analysis was performed on both simulated and experimental torque (equivalent to 20% MVC). In addition, coherence analysis was performed on several simulated neuronal and biomechanical variables. The results suggest that Ia afferents are largely involved in the lowfrequency fluctuations of plantar flexion torque.

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Clonus is explained from increased reflex gain and enlarged tissue viscoelasticity

Cited by 16 publications

References 27 publications

Modeling and Identification of a Realistic Spiking Neural Network and Musculoskeletal Model of the Human Arm, and an Application to the Stretch Reflex

Modeling and Identification of a Realistic Spiking Neural Network and Musculoskeletal Model of the Human Arm, and an Application to the Stretch Reflex

Recovery of neuronal and network excitability after spinal cord injury and implications for spasticity

Low-frequency fluctuations of plantar flexion torque in force and position control tasks studied experimentally and by a neuromusculoskeletal model

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