Kibleur, P.

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 electri-
cal 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 nec-
essary 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 muscu-
lar 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 be-
tween 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.