Subventions et des contributions :

Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023)

The task of maintaining upright stance in the human, while seemingly a very simple thing to do, actually involves a complex sensorimotor control system that has to use and integrate sensory information to stay upright. This sensory information comes from three sensory sources: the inner ear (the vestibular system), the main receptors in our skin, joints and muscles (the somatosensory system), and the information coming from our eyes (the visual system). For this grant, two main concentration areas of research will be carried out. The first main concentration area of research will focus on the individual influences of, as well as the integration of, skin and muscle sensory information on the regulation of single spinal motorneurons in balancing human subjects. Over the past 6 years, we have developed extremely stable indwelling (in the muscle) wire recording electrodes, which can be painlessly inserted into any muscle using ultrasound monitoring for verification. Secondly, we have recently developed and piloted two novel techniques (noisey cutaneous vibration or noisey tendon vibration) with which we will investigate the role of different classes of skin receptors or muscle receptors using some computer-controlled and motorized mechanical systems to either selectively stimulate different regions of the skin of the foot-sole, or to stimulate the tendons of the muscles used in the control of standing balance. We plan to look at the interactive effects of both types of peripheral sensory input on human motorneurons while varying the balance task demands of the subject. The second main concentration area will be to investigate the behaviour of human muscle receptor and skin receptors directly using a research technique termed microneurography. Using a computer-controlled foot pedal, we will look at the response behavior of single muscle receptors or skin from the footsole of the lower limb, while subjects attempt to balance in a simulated environment (as if they were standing). Secondly, although very difficult, it is possible to record from the single axons from muscle receptors in the ankle muscles and cutaneous receptors from the foot-sole in quietly standing human subjects. Therefore, the final experiments will be carried out in standing human subjects while recording from single cutaneous and muscle receptors from the lower limb during different body loads and during different balancing tasks. The experiments in this grant proposal will provide us with insight into how key somatosensory inputs help modulate motorneurons and contribute to the control of normal standing balance.