In vivo imaging of synapse formation on a growing dendritic arbor.
The form of a neuron's dendritic arbor determines the set of axons with which it may form synaptic contacts, thus establishing connectivity within neural circuits. However, the dynamic relationship between dendrite growth and synaptogenesis is not well understood. To observe both processes simultaneously, we performed long-term imaging of non-spiny dendritic arbors expressing a fluorescent postsynaptic marker protein as they arborized within the optic tectum of live zebrafish larvae. Our results indicate that almost all synapses form initially on newly extended dendritic filopodia. A fraction of these nascent synapses are maintained, which in turn stabilizes the subset of filopodia on which they form. Stabilized filopodia mature into dendritic branches, and successive iterations of this process result in growth and branching of the arbor. These findings support a 'synaptotropic model' in which synapse formation can direct dendrite arborization.
Niell
Cristopher M
CM
Neurosciences Program, Beckman Center, Stanford University, Stanford, California 94305, USA.
Meyer
Martin P
MP
Smith
Stephen J
SJ
D000818:Animals; D015415:Biomarkers; D002450:Cell Communication / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D003712:Dendrites / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011554:Pseudopodia / Q000378:metabolism / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins; D013477:Superior Colliculi / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D013570:Synaptic Membranes / Q000378:metabolism; D014795:Visual Pathways / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism
D015415:Biomarkers; D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; C033652:postsynaptic density proteins; D049452:Green Fluorescent Proteins