System identification for studying motor control.

Author(s)

Renato Naville Watanabe

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2016-02-25

Examining board members

Andre Fabio Kohn; Arturo Forner Cordero; Marcos Duarte; Claudio Garcia; Antonio Carlos Roque da Silva Filho

• Advisor: Andre Fabio Kohn

Abstract

Any active motor task is accomplished by the activation of a motor unit population. However, due to many ethical and technical difficulties the synaptic input to the motoneurons cannot be measured in humans. For these reasons realistic computational models of a motoneuron nucleus and the innervated muscle fibers have an important role in the study of the human control of muscles. However such models are complex and their mathematical analysis is difficult. In this text a system identification approach of a realistic motor unit nucleus model is presented with the objective of obtaining a simpler model capable of representing the transduction of the motor unit nucleus inputs into the muscle force signal associated to that nucleus. The system identification was based on an orthogonal least squares algorithm to find a NARMAX model, the input being the net dendritic excitatory synaptic conductance of the motoneurons and the output being the muscle force signal produced by the motor unit nucleus. The identified model output reproduced the mean behavior of the output from the realistic computational model even for input-output signal pairs not used during the identification process, such as sinusoidally modulated output muscle force signals. Generalized frequency response functions of the motoneuron nucleus were obtained from the identified NARMAX model, and led to an inference that cortical oscillations in the beta band (20 Hz) can affect force control by the spinal cord, an unknown motoneuron nucleus behavior until now. (AU)

• FAPESP's process: 11/21103-7 - Model identification for a human postural control study
• Grantee: Renato Naville Watanabe
• Support Opportunities: Scholarships in Brazil - Doctorate