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Effect of voltage drop within the synaptic cleft on the current and voltage generated at a single synapse
L P Savtchenko1, S N Antropov, S M Korogod
1Unite de Neurocybernetique cellulaire, CNRS/UPR 9041, 13009 Marseille, France. leon@marseille.inserm.fr
Biophysical Journal
|February 29, 2000
Summary
Synaptic geometry, including cleft width and receptor zone size, significantly influences synaptic current. These factors create a voltage divider effect impacting current flow and measurements.
Area of Science:
- Neuroscience
- Computational Biology
- Biophysics
Background:
- Synaptic transmission relies on ion flow through receptor channels.
- The physical geometry of the synapse, including the synaptic cleft, is crucial for signal fidelity.
Purpose of the Study:
- To investigate how synaptic cleft width and receptor zone size affect synaptic current.
- To model the electrical properties of a synapse with a circular contact zone.
Main Methods:
- Developed a computational model of a single synapse.
- Simulated synaptic excitation and extracellular current flow.
- Analyzed the dependence of synaptic current on geometric parameters.
Main Results:
- Extracellular current enters the synaptic cleft and flows into the postsynaptic cell.
- A radial gradient in membrane potential and channel currents was observed, decreasing towards the cleft center.
- Synaptic current magnitude varied with receptor zone radius and cleft width.
Conclusions:
- Synaptic geometry, specifically the cleft's resistance, modulates synaptic currents.
- The interplay between cleft resistance and receptor channel resistance acts as a voltage divider.
- Geometric effects must be considered when estimating channel or synaptic conductance from experimental data.
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