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Bifurcation analysis of nonlinear retinal horizontal cell models. II. Network properties
1Department of Physiology, University of Minnesota School of Medicine, Minneapolis.
Journal of Neurophysiology
|July 1, 1990
Summary
Horizontal cells in fish retina exhibit linearized responses due to synaptic input and calcium current inactivation. Network coupling prevents calcium action potentials, even with minimal gap junctions.
Area of Science:
- Neuroscience
- Computational Biology
- Retinal Physiology
Background:
- Previous models of isolated fish horizontal cells utilized bifurcation theory.
- Key findings included the necessity of inactivating inward Ca2+ current and the role of synaptic conductance in model behavior.
Purpose of the Study:
- To extend previous analyses to large networks of coupled horizontal cells.
- To investigate network responses to various stimuli and analyze stability properties.
Main Methods:
- Developed a network model of coupled horizontal cells with nonlinear membrane currents.
- Employed Newton iteration with conjugate gradient (CG) algorithms for network response computation.
- Analyzed network stability by computing network I-V curves under voltage clamp.
Main Results:
- Network coupling with conductance >100 pS prevents Ca2+ action potential generation.
- This critical coupling conductance is equivalent to as few as two gap-junction channels.
- Identified that tonic synaptic input and Ca2+ current inactivation linearize horizontal cell responses.
Conclusions:
- Minimal gap-junction coupling significantly impacts network stability in horizontal cells.
- Computational models are crucial for understanding complex retinal network dynamics.
- Horizontal cell networks demonstrate robust mechanisms for signal processing and stability.