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From contact to connection: early events during synaptogenesis
1Dept of Zoology and Genetics, Iowa State University, Ames 50011, USA.
Trends in Neurosciences
|April 1, 1995
Summary
Neurons form chemical synapses rapidly. Some neurons secrete transmitters before target contact, forming many synapses that refine later, while others require specific signals for precise connections.
Area of Science:
- Neuroscience
- Cell Biology
- Synaptic Plasticity
Background:
- Chemical synapses form rapidly upon initial neuronal contact.
- Neurons often pre-synthesize synaptic components via intrinsic programs.
- Target contact can activate intracellular signals to assemble existing synaptic machinery.
Purpose of the Study:
- To propose distinct mechanisms for chemical synapse formation in 'promiscuous' and 'selective' neurons.
- To elucidate the roles of intrinsic programs versus target-dependent signaling in synapse development.
Main Methods:
- Conceptual model proposed based on existing literature and experimental observations.
- Analysis of signaling pathways involved in synapse assembly and refinement.
Main Results:
- 'Promiscuous' neurons secrete neurotransmitters presynaptically before target contact, leading to abundant synapse formation.
- These over-abundant synapses undergo activity-dependent refinement.
- 'Selective' neurons maintain initial connectivity and require coordinated retrograde and anterograde signaling for accurate matching.
Conclusions:
- Synapse formation involves distinct strategies: early, 'promiscuous' secretion followed by refinement, or precise, signaling-dependent matching.
- Activity-dependent refinement plays a crucial role in shaping neuronal connectivity.