Distal Gap Junctions and Active Dendrites Can Tune Network Dynamics
Open Access
- 1 March 2006
- journal article
- Published by American Physiological Society in Journal of Neurophysiology
- Vol. 95 (3), 1669-1682
- https://doi.org/10.1152/jn.00662.2005
Abstract
Gap junctions allow direct electrical communication between CNS neurons. From theoretical and modeling studies, it is well known that although gap junctions can act to synchronize network output, they can also give rise to many other dynamic patterns including antiphase and other phase-locked states. The particular network pattern that arises depends on cellular, intrinsic properties that affect firing frequencies as well as the strength and location of the gap junctions. Interneurons or GABAergic neurons in hippocampus are diverse in their cellular characteristics and have been shown to have active dendrites. Furthermore, parvalbumin-positive GABAergic neurons, also known as basket cells, can contact one another via gap junctions on their distal dendrites. Using two-cell network models, we explore how distal electrical connections affect network output. We build multi-compartment models of hippocampal basket cells using NEURON and endow them with varying amounts of active dendrites. Two-cell networks of these model cells as well as reduced versions are explored. The relationship between intrinsic frequency and the level of active dendrites allows us to define three regions based on what sort of network dynamics occur with distal gap junction coupling. Weak coupling theory is used to predict the delineation of these regions as well as examination of phase response curves and distal dendritic polarization levels. We find that a nonmonotonic dependence of network dynamic characteristics (phase lags) on gap junction conductance occurs. This suggests that distal electrical coupling and active dendrite levels can control how sensitive network dynamics are to gap junction modulation. With the extended geometry, gap junctions located at more distal locations must have larger conductances for pure synchrony to occur. Furthermore, based on simulations with heterogeneous networks, it may be that one requires active dendrites if phase-locking is to occur in networks formed with distal gap junctions.Keywords
This publication has 53 references indexed in Scilit:
- Exploring gap junction location and density in electrically coupled hippocampal oriens interneuronsNeurocomputing, 2006
- Electrical synapses define networks of neocortical GABAergic neuronsTrends in Neurosciences, 2005
- Using Heterogeneity to Predict Inhibitory Network Model CharacteristicsJournal of Neurophysiology, 2005
- Does it Have to be This Complicated? Focus on “Single-Column Thalamocortical Network Model Exhibiting Gamma Oscillations, Spindles, and Epileptogenic Bursts”Journal of Neurophysiology, 2005
- The Combined Effects of Inhibitory and Electrical Synapses in SynchronyNeural Computation, 2005
- Location, location, location (and density) of gap junctions in multi-compartment modelsNeurocomputing, 2004
- Active dendrites and spike propagation in multicompartment models of oriens‐lacunosum/moleculare hippocampal interneuronsThe Journal of Physiology, 2003
- A fundamental oscillatory state of isolated rodent hippocampusThe Journal of Physiology, 2002
- Alternating and Synchronous Rhythms in Reciprocally Inhibitory Model NeuronsNeural Computation, 1992
- Gap junctions between non‐pyramidal cell dendrites in the rat hippocampus (CA1 and CA3 regions): A combined Golgi‐electron microscopy studyJournal of Comparative Neurology, 1985