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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Influences of premotoneuronal command statistics on the scaling of motor output variability during isometric plantar flexion

Full text
Author(s):
Watanabe, Renato N. [1] ; Magalhaes, Fernando H. [1] ; Elias, Leonardo A. [1] ; Chaud, Vitor M. [1] ; Mello, Emanuele M. [1] ; Kohn, Andre F. [1]
Total Authors: 6
Affiliation:
[1] Univ Sao Paulo, Escola Politecn, Dept Telecommun & Control Engn, Biomed Engn Lab, BR-05508010 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Journal of Neurophysiology; v. 110, n. 11, p. 2592-2606, DEC 2013.
Web of Science Citations: 13
Abstract

This study focuses on neuromuscular mechanisms behind ankle torque and EMG variability during a maintained isometric plantar flexion contraction. Experimentally obtained torque standard deviation (SD) and soleus, medial gastrocnemius, and lateral gastrocnemius EMG envelope mean and SD increased with mean torque for a wide range of torque levels. Computer simulations were performed on a biophysically-based neuromuscular model of the triceps surae consisting of premotoneuronal spike trains (the global input, GI) driving the motoneuron pools of the soleus, medial gastrocnemius, and lateral gastrocnemius muscles, which activate their respective muscle units. Two types of point processes were adopted to represent the statistics of the GI: Poisson and Gamma. Simulations showed a better agreement with experimental results when the GI was modeled by Gamma point processes having lower orders (higher variability) for higher target torques. At the same time, the simulations reproduced well the experimental data of EMG envelope mean and SD as a function of mean plantar flexion torque, for the three muscles. These results suggest that the experimentally found relations between torque-EMG variability as a function of mean plantar flexion torque level depend not only on the intrinsic properties of the motoneuron pools and the muscle units innervated, but also on the increasing variability of the premotoneuronal GI spike trains when their mean rates increase to command a higher plantar flexion torque level. The simulations also provided information on spike train statistics of several hundred motoneurons that compose the triceps surae, providing a wide picture of the associated mechanisms behind torque and EMG variability. (AU)

FAPESP's process: 10/12934-0 - Computational simulations for the study of torque variability during a plantar flexion.
Grantee:Renato Naville Watanabe
Support Opportunities: Scholarships in Brazil - Master
FAPESP's process: 13/10433-1 - Discharge properties of motor units from ankle extensor and flexor muscles during sinusoidal modulation of the joint torque and angle
Grantee:Leonardo Abdala Elias
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 11/21103-7 - Model identification for a human postural control study
Grantee:Renato Naville Watanabe
Support Opportunities: Scholarships in Brazil - Doctorate
FAPESP's process: 11/13222-6 - EVALUATION OF INHIBITORY PATHWAYS AND THE EFFECT OF ELECTRICAL NOISE STIMULATION ON PLANTAR FLEXION NEUROMUSCULAR CONTROL
Grantee:Fernando Henrique Magalhães
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 09/15802-0 - Modelling and simulation of torque control by proprioceptive feedback through the nervous system: application to postural control
Grantee:Leonardo Abdala Elias
Support Opportunities: Scholarships in Brazil - Doctorate