Biomechanical model of the primates’ upper limb: design of stimulation protocols for the recovery of reaching movements in tetraplegia
Recent advances in neuroscience led to the development of therapies for paraplegic patients, currently at the stage of clinical trials, that permit to some extent the restoration of the patients’ natural control over their lower limbs through the electrical stimulation of the sensorial input to their spinal cord. Faced with the individual’s
benefits of such therapies, future developments will focus on porting the technology to the upper limbs, thus bringing partial solutions for increasing the quality of life in tetraplegia. Beyond evident anatomical similarities, the primates are the only animals sharing the direct cortico-motoneuronal pathway with humans, making their study necessary to develop strategies of spinal cord stimulation.
Throughout this thesis, a computational model of the primate’s arm is developed on the OpenSim platform from a previously published but now obsolete SIMM model. Skeletal and muscular morphometric data is gathered, adapted and added until the model is validated dynamically, and its ability to reproduce the real animal’s experimental motion in a closed loop is asserted. The model is then used to predict, in the spinal cord, the spatiotemporal patterns of neuronal activation underlying the subject’s motor behaviour during a stereotypical reaching and grasping task. An estimation of the
afferent fibres’ firing rates will be critical to the understanding of the interactions between the stimulation and the neuronal circuitry, and will alleviate challenges faced in recording the normal sensorimotor activity in real time. As such, the model lays some foundations for the development of future therapies.