The effects of eliminating impulse activity on the development of the retinotectal projection in salamanders

Harris, William A.

doi:10.1002/cne.901940203

Cited by 124 publications

(57 citation statements)

References 38 publications

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“…6 K) did provoke similar defects. Thus, consistent with studies in other synaptic systems (Harris, 1980;Verhage et al, 2000;Baines et al, 2001;Misgeld et al, 2002;Varoqueaux et al, 2002;Heeroma et al, 2003), ionic transmission through the postsynaptic neurotransmitter receptors does not appear essential for principal synapse assembly. Instead, our data clearly imply that a critical level of glutamate receptor protein is needed to allow synapse maturation.…”

Section: Discussionsupporting

confidence: 86%

Non-NMDA-Type Glutamate Receptors Are Essential for Maturation But Not for Initial Assembly of Synapses atDrosophilaNeuromuscular Junctions

Schmid

Qin²,

Wichmann³

et al. 2006

J. Neurosci.

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The assembly of glutamatergic postsynaptic densities (PSDs) seems to involve the gradual recruitment of molecular components from diffuse cellular pools. Whether the glutamate receptors themselves are needed to instruct the structural and molecular assembly of the PSD has hardly been addressed. Here, we engineered Drosophila neuromuscular junctions (NMJs) to express none or only drastically reduced amounts of their postsynaptic non-NMDA-type glutamate receptors. At such NMJs, principal synapse formation proceeded and presynaptic active zones showed normal composition and ultrastructure as well as proper glutamate release. At the postsynaptic site, initial steps of molecular and structural assembly took place as well. However, growth of the nascent PSDs to mature size was inhibited, and proteins normally excluded from PSD membranes remained at these apparently immature sites. Intriguingly, synaptic transmission as well as glutamate binding to glutamate receptors appeared dispensable for synapse maturation. Thus, our data suggest that incorporation of non-NMDA-type glutamate receptors and likely their protein-protein interactions with additional PSD components triggers a conversion from an initial to a mature stage of PSD assembly.

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Section: Discussionsupporting

confidence: 86%

Non-NMDA-Type Glutamate Receptors Are Essential for Maturation But Not for Initial Assembly of Synapses atDrosophilaNeuromuscular Junctions

Schmid

Qin²,

Wichmann³

et al. 2006

J. Neurosci.

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“…In the optic tectum of vertebrates, for example, it has been shown that correlated activity in retinal ganglion cells determines the fine distribution of retinal terminals in the tectum. Any perturbation of this pattern of activity leads to defects in the final pattern of connections and therefore in the size and/ or shape of the receptive field of these neurons in the tectum (Harris, 1980;Meyer, 1982;Schmidt and Edwards, 1983). In the vertebrate neuromuscular junction, it has also been shown that disruptions in the level of activity of motor axons lead to changes in morphology of axon terminals (Duchen and Strich, 1968;Brown and Ironton, 1977;Holland and Brown, 1980).…”

Section: An Anatomicalmentioning

confidence: 99%

Morphological plasticity of motor axons in Drosophila mutants with altered excitability

1990

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An anatomical and electrophysiological study of Drosophila mutants has been made to determine the effect of altered electrical activity on the development and maintenance of larval neuromuscular junctions. We examined motor axon terminals of (1) hyperexcitable mutants Shaker (Sh), ether a go-go (eag), Hyperkinetic (Hk), and Duplication of para+ (Dp para+); and (2) mutants with reduced excitability, no action potential (napts) and paralytic (parats 1). Nerve terminals innervating larval body-wall muscles were visualized by using anti-HRP immunocytochemistry, which specifically stains neurons in insect species. In wild-type larvae, motor axon terminals were distributed in a stereotypic fashion. However, in combinations of eag and Sh alleles, the basic pattern of innervation was altered. There was an increase in both the number of higher-order axonal branches over the muscles and the number of varicosities on the neurites. A similar phenomenon was found in the double mutant Hk eag and, to a lesser extent, in Dp para+ and Dp para+ Sh mutants. It is known that at permissive temperature the napts, but not parats 1, mutation decreases excitability of larval motor axons and suppresses the behavioral phenotypes of Sh, eag, and Hk. In the mutant napts (reared at permissive temperature), a slight decrease in the extent of branching was observed. Yet, when combined with eag Sh, napts completely reversed the morphological abnormality in eag Sh mutants. No such reversion was observed in parats 1 eag Sh mutants. The endogenous patterns of electrical activity at the neuromuscular junction were analyzed by extracellular recordings in a semi-intact larval preparation. Recordings from wild-type body-wall muscles revealed rhythmic bursts of spikes. In eag Sh mutants, this rhythmic activity was accompanied by or superimposed on periods of strong tonic activity. This abnormal pattern of activity could be partially suppressed by napts in combination with eag Sh.

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“…In cold-blooded vertebrates, retinal axons grow directly to topographically appropriate regions of the tectum, where they subsequently arborize (14)(15)(16)(17)(18). This phase of map development is independent of activity (19)(20)(21)(22). All subsequent synaptic remodeling, including the refinement and maintenance of topography, occurs when the retina is fully functional and generates mature visual responses (23).…”

mentioning

confidence: 99%

N-methyl-D-aspartate receptor antagonists disrupt the formation of a mammalian neural map.

Simon

Prusky

O’Leary

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

291

152

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The topographic ordering of retinal connections in the rat superior colliculus emerges during early postnatal Ilfe from an initially diffuse projection. Disruption of N-methyl-D-aspartate (NMDA) receptor activity in the superior colliculus during this period interferes with map remodeling. In rats chronically treated with NMDA receptor antagonists during the first two postnatal weeks, aberrant axons remain and arborize at topographically incorrect sites. These results indicate that, at a stage preceding visually evoked activity, normal NMDA receptor function is important for the development of an ordered neural map in the mammalian brain.

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The effects of eliminating impulse activity on the development of the retinotectal projection in salamanders

Cited by 124 publications

References 38 publications

Non-NMDA-Type Glutamate Receptors Are Essential for Maturation But Not for Initial Assembly of Synapses atDrosophilaNeuromuscular Junctions

Non-NMDA-Type Glutamate Receptors Are Essential for Maturation But Not for Initial Assembly of Synapses atDrosophilaNeuromuscular Junctions

Morphological plasticity of motor axons in Drosophila mutants with altered excitability

N-methyl-D-aspartate receptor antagonists disrupt the formation of a mammalian neural map.

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