Spinal cord injury (SCI) is devastating and leaves patients unable to independently complete even the most routine, daily tasks such as walking, holding objects, or getting dressed. Therefore, it is imperative to restore movement to the paralyzed limbs of SCI patients so that they can reestablish their independence. One promising technique called functional electrical stimulation (FES) bypasses the central lesion to restore movement in a paralyzed limb by artificially stimulating peripheral nerves or muscles to reanimate the limb. Current approaches for FES have improved motor function and enabled patients to control a few, pre-programmed movements, but rely on control strategies that are unable to restore more complicated behaviors. These control strategies fail to effectively control both the highly nonlinear dynamics of the musculoskeletal system and the redundant musculature of the limb. In this research, we will design a novel FES control strategy that overcomes these complexities of motor control by using basic, experimental ideas for how the central nervous system innately orchestrates movements. To achieve this, we will first develop our control strategy that uses muscle synergies to exploit the properties and dynamics of the musculoskeletal system (Aim 1). We will use techniques of system balancing to empirically form a low-dimensional representation of the limb that captures its natural dynamics and uses muscle synergies for control. Then, we will evaluate the potential of our control strategy to be used in FES systems by comparing its performance to a state-of-the-art, model-based FES control strategy (Aim 2). We will implement the two control strategies in a paralyzed rat hindlimb to directly quantify their performances. We expect our control strategy to exceed the performance measures of the model-based FES control strategy. For that reason, we strongly believe our biologically-inspired control strategy will greatly improve the ability to control movement in clinical FES systems. More than 200,000 people suffer from SCI and 10,000 more injuries occur each year. This research has the potential to significantly affect both the psychological and financial costs of SCI at both the individual and societal levels by restoring natural behavior. By demonstrating and evaluating our FES control strategy in a paralyzed limb, we will form a foundation to translate this technology to clinical applications.
| Berniker, M; Jarc, A; Kording, K et al. (2016) A Probabilistic Analysis of Muscle Force Uncertainty for Control. IEEE Trans Biomed Eng 63:2359-2367 |
| Jarc, Anthony M; Berniker, Max; Tresch, Matthew C (2013) FES control of isometric forces in the rat hindlimb using many muscles. IEEE Trans Biomed Eng 60:1422-30 |
