Grant: Discovery Grants Program - Individual

When making goal-directed voluntary movements the human central nervous system (CNS) processes sensory input and engages in response planning involving various cortical and subcortical CNS structures. However, it remains unclear how changes in neural state at various levels of the CNS reflect these processes. Understanding how the human nervous system components work together is fundamental to understanding how humans organize and execute complex actions. The long-term objective of my research program is to clarify how different CNS structures contribute to the preparation and initiation of voluntary movement. To meet this objective, my lab combines behavioural studies, neurophysiological techniques, and modelling approaches in novel ways to investigate human motor preparation and initiation from various perspectives and levels of analysis. The present proposal seeks to establish the nature of the neural excitability in cortical and reticular CNS structures underlying preparation, initiation, and execution of goal-directed movements in humans. Recent work in my lab has highlighted the particularly overlooked role of the reticulospinal system in voluntary movement production in humans. While the contribution of the reticulospinal system to postural control is well researched, its role in upper limb voluntary action is less clear. In addition, the timeline of neural activation in reticular and other CNS structures responsible for motor preparation and initiation is not well understood relative to other processes. In order to accomplish the goal of the present proposal we will pursue several specific and feasible aims: 1) To understand the mechanisms underlying changes in corticospinal excitability preceding response initiation under different task requirements, 2) To further elucidate the role of the reticulospinal system in the preparation and initiation of movements, and 3) To clarify changes in the background motor unit firing in the musculature preceding voluntary action. These objectives will involve studies that combine behavioural manipulations and outcomes such as reaction time, with neurophysiological techniques such as transcranial magnetic stimulation and motor unit decomposition of electromyography. This work has the potential to be highly impactful as the role of the reticulospinal system in the production of voluntary movements is underappreciated, and findings from this research may provide an alternative pathway for rehabilitation (e.g., increased engagement of reticular structures). Also, HQP trainees from diverse backgrounds will gain technical expertise, analysis skills, and dissemination experience. Finally, this work has strong implications for several areas of research and is not limited to human motor control. The findings from this research can inform human and animal neuroscience, clinical neurophysiology, psychology, and areas of applied research such as the development of new interventions and technologies.