Judith L. Smith, Ph.D.


Professor, Integrative Biology and Physiology
Vice Provost, College of Letters and Science
Undergraduate Education
Member, Brain Research Institute

Contact Information



Neural control of stereotypic limb motions with and without motion-dependent feedback and/or in the absence of specific supraspinal input Research Description: My research focuses on the neural control of stereotypic and cyclic limb movements; I use the cast as an animal model. Particularly, I am concerned with those cyclic motions of the cat's hindlimb that are programmed primarily by circuits within lumbosacral segments, such as walking, scratching, and paw shaking. In studying these movements, I attempt to determine which parameters are controlled primarily by central circuits (the immutable features) and which parameters depend on the interaction between movement-related feedback and the central network (the mutable features). To determine the mutable and immutable features, I externally perturb the limb (e.g., joint immobilization) and/or determine internal perturbations provided by the moving limb's intersegmental dynamics. Patterns of synergistic muscle activity are recorded with surgically-implanted electrodes and the resultant hindlimb actions are recorded on high-speed cinematographic film. Also, I perturb the controlling neural elements using techniques such as deafferentation, spinal lesions, or neuropharmacological infiltrations. I am also interested in how central pattern generators are organized developmentally in mammals (kittens, prior to birth and up to 2 mo old) and how spinal circuits are organized so that more than on cyclical movement can be controlled (in part) by the same central pattern generator. The primary objective of the laboratory is to understand how neuronal circuits within the spinal cord organize various stereotypic motions with and without motion-dependent feedback and/or in the absence of specific supraspinal input.