Project Summary: Disruption of the corticospinal pathway following spinal cord injury or stroke is known to drastically debilitate skilled locomotion. This pathway is mainly involved in bridging and decoding sensory information to be translated for the selection or modification of an optimal motor program to accomplish an intended task. It has also been recently found to be implicated in modulating pain following peripheral nerve injury. The exact mechanisms at which it operates, however, has not yet been revealed. Hence, the goal of this study is to shed light on these mechanisms by designing and implementing optical stimulation protocols to deconstruct these neural circuits and selectively manipulate corticospinal neurons' activity in the cortex followed by behavioural and motor outcome assessment.