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Electrical coupling between model midbrain dopamine neurons: effects on firing pattern and synchrony.
Alexander O Komendantov1, Carmen C Canavier
1Department of Psychology, University of New Orleans, New Orleans, LA 70148, USA.
Journal of Neurophysiology
|March 6, 2002
Summary
Electrical coupling between dopamine neurons influences their firing patterns, facilitating burst firing through two distinct mechanisms. This finding helps explain why burst firing is more readily observed in vivo.
Area of Science:
- Neuroscience
- Computational Neuroscience
Background:
- Gap junctions between midbrain dopamine (DA) neurons play a role in firing pattern generation and synchronization.
- The precise mechanisms and experimental characterization of this role remain limited.
Purpose of the Study:
- To investigate the influence of electrical coupling via gap junctions on the firing patterns of midbrain dopamine neurons.
- To elucidate the mechanisms by which electrical coupling affects burst firing in these neurons.
Main Methods:
- A multi-compartment model of a dopamine neuron was developed, incorporating a spike-generating mechanism.
- Two model neurons were electrically coupled through their dendrites using gap junctions.
- Simulations explored firing patterns under varying N-methyl-D-aspartate (NMDA)-induced current permeability and electrical coupling conductance.
Main Results:
- Electrical coupling was found to facilitate NMDA-induced burst firing through two mechanisms: one in identical neuron pairs and another in heterogeneous pairs.
- In identical neurons, coupling influenced transitions between asynchronous/synchronous spiking and burst firing, depending on NMDA levels and coupling strength.
- In heterogeneous neurons, coupling biased cells into burst firing regimes, independent of action potential dynamics.
Conclusions:
- Electrical coupling significantly modulates dopamine neuron firing patterns, promoting burst firing.
- The findings suggest that gap junction activity in vivo may contribute to the higher prevalence of observed NMDA-induced burst firing compared to in vitro preparations.