Functional Properties of Dendritic Gap Junctions in Cerebellar Golgi Cells.
Neuron. 2016-06-01; 90(5): 1043-1056
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Neuron. 2016 Jun 1;90(5):912-4.
The strength and variability of electrical synaptic connections between GABAergic
interneurons are key determinants of spike synchrony within neuronal networks.
However, little is known about how electrical coupling strength is determined due
to the inaccessibility of gap junctions on the dendritic tree. We investigated
the properties of gap junctions in cerebellar interneurons by combining paired
somato-somatic and somato-dendritic recordings, anatomical reconstructions,
immunohistochemistry, electron microscopy, and modeling. By fitting detailed
compartmental models of Golgi cells to their somato-dendritic voltage responses,
we determined their passive electrical properties and the mean gap junction
conductance (0.9 nS). Connexin36 immunofluorescence and freeze-fracture replica
immunogold labeling revealed a large variability in gap junction size and that
only 18% of the 340 channels are open in each plaque. Our results establish that
the number of gap junctions per connection is the main determinant of both the
strength and variability in electrical coupling between Golgi cells.