Investigation of the synchronism between pairs of motor units from Soleus and Gastrocnemius muscles during isometric contractions and postural control

• Grant number: 14/24385-1
• Support Opportunities: Scholarships abroad - Research
• Start date: January 20, 2015
• End date: February 19, 2015
• Field of knowledge: Engineering - Biomedical Engineering - Bioengineering
• Principal Investigator: Leonardo Abdala Elias
• Grantee: Leonardo Abdala Elias
• Host Investigator: Dario Farina
• Host Institution: Faculdade de Engenharia Elétrica e de Computação (FEEC). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: Göttingen University, Germany

Abstract

The performance of a given motor task is largely influenced by the neural drive to the muscles, which is provided by the spinal motor neurons (MNs). Therefore, the way these MNs integrate a plethora of neural signals from different sources is determinant to mold the motor output. One factor that is known to influence the force control is the degree of synchronism (or correlation) between the motor units from a muscle. This synchronous activity is generated by common inputs impinging onto a subset (or the whole population) of motor neurons. Experimental results tried to elucidate which common inputs might be driving the motor units of a specific muscle during a given motor task. However, in several motor tasks, for instance during upright stance control and isometric plantarflexion contractions, there are several synergist muscles (e.g., Soleus, Medial and Lateral Gastrocnemius) responsible for the force (torque) generation and control. In this project the aim is to perform an analysis of the synchronism between pairs of motor units from the Soleus and Gastrocnemius (medial and lateral parts) muscles that are active during the performance of isometric platarflexion contractions and also during upright stance control. High-density electromyography will be used to record signals from these muscles and an automated decomposition algorithm will be used to obtain the spike trains from several motor units. These spike trains will be used to perform time- and frequency-domain analyses so as to investigate the common inputs to the motor units from different muscles. Different force levels and joint positions will be evaluated during the isometric contractions so as to investigate to what extent the voluntary command and proprioceptive inputs would influence the degree of correlation between the neural drive to synergist muscles.