The proper functioning of the adult nervous system requires not only that neurons develop and interconnect properly during the embryonic period, but also that they retain some degree of plasticity in postembryonic life. As the nervous system matures, existing neurons may be modified to participate in new behavior. The primary objectives of this proposal are to understand the extent to which existing neurons can be modified structurally and functionally during postembryonic life, how these modifications are related to behavioral change, and how this plasticity is induced and regulated. Answers to these important questions require a simple model system in which it is possible to identify individual neurons and follow them as they are modified postembryonically. The experiments in this proposal concentrate upon the neural reorganization that accompanies insect metamorphosis, specifically upon the circuitry controlling the larval and adult legs of the moth, Manduca sexta. Although many of the same neurons are retained, the function of the legs is quite different in two stages. These retained neurons must delete synaptic connections important for larval behavior and form new interconnections appropriate for driving the adult legs. In this simple model system, intracellular recording techniques will be used to identify individual motorneurons, sensory neurons, and interneurons and to inject persistent marker molecules which will be used to follow these cells through metamorphosis.
Specific aims are to determine which neurons are modified structurally and functionally, and to relate these modifications to changes in behavior. Furthermore, just as steroid hormones are known to influence the development of vertebrate nervous systems, steroid and steroid-like hormones are important regulators of insect metamorphosis. Precise hormonal manipulations, including the introduction of steroids into individual neurons, will be used in the future to pursue the mechanisms responsible for the induction of neural plasticity. These experiments will result in a better understanding of the cellular mechanisms underlying the development of normal neural function, and provide a model system which may be useful in the future for investigating the molecular mechanisms involved in neuronal differentiation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS024822-01
Application #
3409740
Study Section
Neurology B Subcommittee 1 (NEUB)
Project Start
1987-07-01
Project End
1990-06-30
Budget Start
1987-07-01
Budget End
1988-06-30
Support Year
1
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Arizona
Department
Type
Organized Research Units
DUNS #
City
Tucson
State
AZ
Country
United States
Zip Code
85722
Johnston, Rebecca M; Levine, Richard B (2002) Thoracic leg motoneurons in the isolated CNS of adult Manduca produce patterned activity in response to pilocarpine, which is distinct from that produced in larvae. Invert Neurosci 4:175-92
Bayline, R J; Duch, C; Levine, R B (2001) Nerve-muscle interactions regulate motor terminal growth and myoblast distribution during muscle development. Dev Biol 231:348-63
Consoulas, C; Duch, C; Bayline, R J et al. (2000) Behavioral transformations during metamorphosis: remodeling of neural and motor systems. Brain Res Bull 53:571-83
Rose, U; Levine, R B (2000) Comparison of identified leg motoneuron structure and function between larval and adult Manduca sexta. J Comp Physiol A 186:327-36
Consoulas, C (2000) Remodeling of the leg sensory system during metamorphosis of the hawkmoth, Manduca sexta. J Comp Neurol 419:154-74
Consoulas, C; Johnston, R M; Pfluger, H J et al. (1999) Peripheral distribution of presynaptic sites of abdominal motor and modulatory neurons in Manduca sexta larvae. J Comp Neurol 410:4-19
Consoulas, C; Levine, R B (1998) Presynaptic function during muscle remodeling in insect metamorphosis. J Neurosci 18:5817-31
Lemon, W C; Levine, R B (1997) Segmentally distributed metamorphic changes in neural circuits controlling abdominal bending in the hawk moth Manduca sexta. J Comp Physiol A 180:597-610
Consoulas, C; Anezaki, M; Levine, R B (1997) Development of adult thoracic leg muscles during metamorphosis of the hawk moth Manduca sexta. Cell Tissue Res 287:393-412
Consoulas, C; Levine, R B (1997) Accumulation and proliferation of adult leg muscle precursors in Manduca are dependent on innervation. J Neurobiol 32:531-53

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