In vivo two-photon imaging methods will be used to explore the mechanisms of dendrite growth and synaptogenesis in the zebrafish retinotectal pathway. The project will focus especially on effects of visually stimulated activity on dendrite growth and synaptogenesis. The zebrafish tectum is very well suited to two-photon fluorescence imaging, and development of the retinotectal projection is known to depend on activity. Novel genetically encoded fluorescent protein (FP) markers and automated two-photon (2P) microscopy will be used to efficiently study dynamics of dendritic arbor growth and synaptogenesis at high time resolution over long time periods. The research involves four specific aims: (1) determine kinetic parameters of dendrite growth and synaptogenesis under baseline (dark, unstimulated) conditions, (2) measure effects of defined visual stimuli on kinetic parameters of dendrite growth and synaptogenesis, (3) test selective glutamate receptor antagonists for effects on growth and synaptogenesis parameters under baseline and visual stimulation conditions, and (4) measure and analyze dendritic Ca transients evoked by patterned visual stimulation. These studies will be among the first to integrate dynamic imaging of dendritic arbor growth with visualization of synaptogenesis processes. Experiments based on this new capability will test various current hypotheses relating the dynamics of dendrite growth and synaptogenesis to each other and to the activity-dependent development of functional neural circuitry. To understand normal or pathological brain development, it is obviously necessary to understand dendrite growth and synaptogenesis. It now appears that dendrite growth and synaptogenesis processes may persist in mature brains, as well, so our studies of these processes in developing zebrafish may advance understanding of the plasticity and pathologies of mature nervous systems. In addition, the developmental insights obtained may point to unexpected therapeutic opportunities for treating disorders of vision, and repairing effects of neurological trauma, neurodegeneration, and drug addiction.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS043461-03
Application #
6890403
Study Section
Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
Program Officer
Mamounas, Laura
Project Start
2003-07-01
Project End
2008-04-30
Budget Start
2005-05-01
Budget End
2006-04-30
Support Year
3
Fiscal Year
2005
Total Cost
$375,862
Indirect Cost
Name
Stanford University
Department
Biophysics
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
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Niell, Cristopher M (2006) Theoretical analysis of a synaptotropic dendrite growth mechanism. J Theor Biol 241:39-48
Niell, Cristopher M; Smith, Stephen J (2005) Functional imaging reveals rapid development of visual response properties in the zebrafish tectum. Neuron 45:941-51
Niell, Cristopher M; Meyer, Martin P; Smith, Stephen J (2004) In vivo imaging of synapse formation on a growing dendritic arbor. Nat Neurosci 7:254-60