USU Neuroscience

rborke@usuhs.mil
 
Ph.D., George Washington University, 1979
 
Plastic Responses of neurons during development and regeneration
 
The research program in this laboratory is focused on plastic responses of motoneurons during development and regeneration. The major interest is to gain an understanding of developmentally-regulated substances that are re-expressed after nerve injury to adult motoneurons. Studies center on two different types of substances: those that are produced at high levels during ontogeny and either progressively decline to low levels (CGRP) or are not detectable (NGF receptor, NGF) in intact adult motoneurons. Developmental plasticity studies involve 1) defining profiles of gene expression and 2) determining the types of signal transfer mechanisms that regulate changes in the levels of expression of these substances during ontogeny. Experiments involve surgical and chemical manipulation of central (local neuropil environment around the motoneuron) and peripheral (target site of motoneuron) developmental events to examine whether the down-regulation in intact motoneurons is coincident with a defined phase of glial development and if it is controlled by events at the growing tip of the axon, the postsynaptic neuromuscular junction or presynaptic input to the motoneuron.
 
The other phase of research is to investigate the role of these substances to changes in and around axotomized adult motoneurons that are considered germane to regeneration: whether the up-regulation of these substances influences anterograde (growing axonal tip at the injury site and reinnervation of the target site) and retrograde (glial reaction and afferent synaptic displacement) regenerative processes. Techniques utilized in carrying out this research program include general and stereotaxic surgery, immunocytochemistry, image analysis, the polymerase chain reaction, as well as horseradish peroxidase labeling and nerve stimulation to assay anatomic and functional reinnervation.
 
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