Grant: Discovery Grants Program - Individual

During terrestrial locomotion, inputs from specialized receptors that respond to mechanical stimuli (mechanoreceptors) located in muscles, tendons, joints, and skin, inform the central nervous system of the body segments' relative position and motion, the forces that muscles generate and exert on bones, as well as characteristics of the terrain. The long-term goal of this research program is to determine the specific roles of somatosensory feedback in controlling locomotion. Particularly, I am interested in how the relative contribution of somatosensory feedback changes with task demands and how the nervous system reorganizes its output in a somatosensory-deprived state. To address our long-term goal in the next five years, we have three short-term objectives. We will determine the contribution of somatosensory feedback in shaping locomotor outputs with a change in speed (Objective 1), direction (Objective 2) and during skilled locomotion (Objective 3). We will use the cat model and abolish or diminish somatosensory feedback by destroying primary afferents using pyridoxine (Vitamin B6) intoxication. Pyridoxine intoxications destroys large primary afferents involved in proprioception and possibly touch, greatly affecting posture and locomotion. We will quantify changes in kinematics and muscle activity, including a characterization of muscle synergies, in the same animals before and after pyridoxine intoxication during treadmill and overground locomotion at different speeds, in different directions and in skilled tasks. The proposed studies will generate high quality behavioural and electrophysiological data, advancing knowledge by providing a greater depth of understanding on how somatosensory feedback contributes to locomotor control. Our experimental approach, which uses established techniques in the cat model, allows us to link neural mechanisms to the "real world" of sensorimotor control. These links allow experiments in cats that closely parallel experiments that are achievable in humans, providing a strong translational potential for human research. Our studies are cited by a variety of knowledge users in different fields, such as neuroscience, robotics, engineering, kinesiology, veterinary medicine and rehabilitation. One application of this work is the design of motor prostheses to improve quality of life for users. Indeed, one of the major challenges is correcting movement errors in people with movement disorders because of the loss of proprioceptive and tactile feedback. Vision can only accomplish so much without somatosensory information from the limbs and trunk. Another application is the design of biologically-inspired robots where control systems make use of sensors to guide and adjust their movements. Highly qualified personnel will have the opportunity to train in an interdisciplinary environment with physiologists, engineers, computational neuroscientists and clinicians.