Title: The role of proprioception in target-directed reaching.
Thesis Supervisors: J. Timothy Inglis; Romeo Chua
Committee Member: Hyosub Kim
Chair: Kayla Fewster
Abstract:In order to successfully navigate our environment, the central nervous system (CNS) must have accurate information regarding the state of our musculoskeletal system. This sense, which is known as proprioception, can be defined as the awareness of the mechanical and spatial state of the body and its musculoskeletal parts. The CNS relies on information from peripheral proprioceptors located in muscles, joints, and skin to estimate the current state of the musculoskeletal system. Accurate limb position estimation is crucial for performing goal-directed movements, such as reaching for a cup of coffee. However, it remains unclear how the CNS utilizes proprioceptive feedback from muscle receptors, which signal characteristics such as muscle length, to execute these movements. A key process in interacting with the environment is the transformation of proprioceptive feedback into visual (extrinsic) coordinates. The primary aim of this thesis is to investigate the processes by which the CNS uses proprioceptive feedback to produce goal-directed reaches that require limb position to be expressed in visual coordinates. The first three studies of this thesis will investigate how the CNS uses and integrates proprioceptive feedback from muscles around a joint to estimate the position of the hand. The findings from these studies will provide foundational knowledge of the basic processes that the CNS may use when integrating proprioceptive feedback from the periphery. The fourth study in this thesis will investigate the nature of the errors that occur when the proprioceptive feedback has to be transformed into visual coordinates. This study will help elucidate the nature of proprioceptive biases that have been found in many studies. The final two studies in this thesis will investigate how this proprioceptive to visual transformation process can be dynamically modified in response to sensory error signals. Overall, the findings from this thesis will provide a more detailed insight into the processes that the CNS uses to integrate proprioceptive feedback for goal directed movements.