The central nervous system (CNS) has to combine many degrees of freedom available in the human musculoskeletal system to generate a coordinated motor behaviour. There is a growing body of work that supports the existence of a synergistic motor control mechanism utilized by the CNS to facilitate motor coordination. The theory of motor synergies suggests that the CNS controls groups of muscles and/or joints rather than controlling each muscle or joint separately, effectively reducing the high dimensionality of motor planning and execution. Recent studies with stroke survivors suggest that motor impairment after stroke is due to the disruption caused by the cortical lesion in the recruitment and the combination of the motor synergies.
The objective of this proposed work is to investigate human upper body motor coordination and to demonstrate the viability of synergistic motor control theory in describing the natural upper body movements, as well as quantifying the effects of stroke on motion generation. As part of this proposed work, I will also investigate the process of motor recovery after stroke by describing how motor synergies change as stroke-survivors complete a conventional physical therapy regimen.
The main contributions of this work will be:
- Proposal of a symmetrical bimanual motor exploration task to study healthy and stroke affected motor synergies (i.e., kinematic or muscle synergies)
- Investigation of robustness of analytical methods and metrics reported in literature in characterizing motor synergies of the healthy and clinical populations
- Providing an understanding of the differences between motor synergies of the dominant and non-dominant hands of healthy adults (within-subject differences) and whether there is a set of “healthy” motor synergies shared within this population (between-subjects differences)
- Providing an understanding of the effects of stroke on motor control, specifically whether the strong side of the body utilizes the “healthy” synergy set and whether motor impairment after stroke is due to dysfunctional activation of synergies or due to disruption in the structure of synergies
- Proposal of motor synergies as a clinical score to quantify the motor recovery process after stroke and answering fundamental questions about the nature of this process
A better understanding of motor synergies may improve rehabilitation practices by identifying strengthening physical therapy exercises that utilize or promote the use of “healthy” synergies while avoiding reinforcement of undesirable compensatory movement patterns.
Researcher: Navid Lambert-Shirzad
Supervisor: Dr. Mike Van der Loos
Committee Members: Dr. Anthony Hodgson, Dr. Elizabeth Croft, Dr. Nicola Hodges, Dr. Lara Boyd