As the nervous system develops, synaptic connections between nerve cells are initially established in a highly specific manner. These initial contacts can then be modified to a limited extent, increasing their specificity still further. A knowledge of the functional and morphological correlates of synaptic development in the central nervous system is basic to an understanding of how nerve cells originally make and then refine and maintain their proper connections. Synaptic connections in the spinal cord between muscle sensory afferent fibers and motoneurons, connections which form the neuronal basis of the stretch reflex, provide an excellent experimental system for studying this problem at the level of single, functionally identified cells. In the frog's spinal cord, these connections form with a high degree of specificity and undergo only limited modifications thereafter. Vestibular inputs to these same motoneurons are also specific in adult frogs, but the manner in which this specificity develops in unknown. A major aim of this proposal is to compare the development of these two sensory inputs to gain insights into how specific synapses are formed. Sensory fibers in the frog can also regenerate after they are cut in the dorsal root, and they re-innervate motoneurons with a high degree of specificity. A continued study of the factors that influence the amount and specificity of this regeneration could help in achieving specific regeneration in human spinal cord after accidental injury. My objectives during the next five years are as follows: 1) Study the normal development of monosynaptic connections between muscle sensory axons and motoneurons at the level of individual functionally identified cells. 2) Extend these studies to the development of the vestibulospinal input to forelimb motoneurons. 3) Examine the effects of types of lesions on the extent of regeneration of sensory dorsal root axons into the spinal cord.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS024373-03
Application #
3408889
Study Section
Neurology C Study Section (NEUC)
Project Start
1986-04-01
Project End
1989-03-31
Budget Start
1988-04-01
Budget End
1989-03-31
Support Year
3
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Type
Schools of Medicine
DUNS #
053785812
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Wang, Zhi; Li, LingYing; Frank, Eric (2012) The role of muscle spindles in the development of the monosynaptic stretch reflex. J Neurophysiol 108:83-90
Wang, Zhi; Li, LingYing; Goulding, Martyn et al. (2008) Early postnatal development of reciprocal Ia inhibition in the murine spinal cord. J Neurophysiol 100:185-96
Hardy, W Rod; Li, Lingying; Wang, Zhi et al. (2007) Combinatorial ShcA docking interactions support diversity in tissue morphogenesis. Science 317:251-6
Wang, Zhi; Li, Ling Ying; Taylor, Michael D et al. (2007) Prenatal exposure to elevated NT3 disrupts synaptic selectivity in the spinal cord. J Neurosci 27:3686-94
Li, L Y; Wang, Z; Sedy, J et al. (2006) Neurotrophin-3 ameliorates sensory-motor deficits in Er81-deficient mice. Dev Dyn 235:3039-50
Oakley, R A; Lefcort, F B; Plouffe, P et al. (2000) Neurotrophin-3 promotes the survival of a limited subpopulation of cutaneous sensory neurons. Dev Biol 224:415-27
Chen, H H; Frank, E (1999) Development and specification of muscle sensory neurons. Curr Opin Neurobiol 9:405-9
Sharma, K; Frank, E (1998) Sensory axons are guided by local cues in the developing dorsal spinal cord. Development 125:635-43
Oakley, R A; Lefcort, F B; Clary, D O et al. (1997) Neurotrophin-3 promotes the differentiation of muscle spindle afferents in the absence of peripheral targets. J Neurosci 17:4262-74
Mears, S C; Frank, E (1997) Formation of specific monosynaptic connections between muscle spindle afferents and motoneurons in the mouse. J Neurosci 17:3128-35

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