Download Nathan Bunderson

SUBJECT:
Ph.D. Proposal Presentation
BY:
Nathan Bunderson
DATE
Monday, December 19, 2005, 1:00pm
LOCATION:
U.A. Whitaker Building, Room 1214
TITLE:
The Role of Heterogenic Spinal Reflexes in Coordinating
and Stabilizing the Feline Hindlimb
COMMITTEE:
Advisor: Thomas Burkholder, Ph.D. (Georgia Institute of
Technology
T. Richard Nichols, Ph.D. (Emory University)
Lena Ting, Ph.D. (Georgia Institute of Technology, Emory
University)
Shawn Hochman, Ph.D. (Emory University)
Roman Griogoriev, Ph.D. (Georgia Institute of Technology)
SUMMARY
A fundamental question in motor control theory is the relative importance of supraspinal
control signals and the peripheral neuromuscular system, which includes both intrinsic
musculoskeletal properties and spinal reflex pathways. Understanding the peripheral
neuromuscular organization will lead to improved rehabilitation for spinal cord injury
patients and treatment of diseases that affect this system, such as large fiber sensory
neuropathies, and has direct application in the fields of prosthetics, neuroprosthetics,
and industrial robotics. The goal of this proposal is to determine the role of heterogenic
spinal reflexes in coordinating the control of limbs. The wide distribution of heterogenic
feedback across joints and the dynamic nature of that feedback are uniquely suited to
integrating the limb response to perturbation and simplifying control of dynamic motions.
Such a role for the heterogenic reflex could serve to reduce the computational demands
of postural control and movement planning on the CNS. The hypothesis under
investigation is that heterogenic length and force feedback integrate joint excursions and
stabilize the limb. We test this hypothesis by evaluating the impact of heterogenic
reflexes on the stability and coordination of a feline hindlimb. The methods for
determining coordination and stability are developed first in simulations of a simplified
mathematical model and then expanded to an anatomically based model incorporating
neuromuscular architecture. This includes segmental inertias, muscle mechanical
connectivity, and multiple layers of reflex feedback. Finally, the model will be compared
with the actual limb kinematics of cats using motion capture techniques.