Analysis of rod/cone gap junctions from the reconstruction of mouse photoreceptor terminals.

Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization, and noise reduction in neuronal circuits. In addition, gap junctions may also provide alternative neuronal pathways. However, because they are small and especially difficult to image, gap junctions are often ignored in large-scale 3D reconstructions.

Molecular and functional architecture of the mouse photoreceptor network.

Mouse photoreceptors are electrically coupled via gap junctions, but the relative importance of rod/rod, cone/cone, or rod/cone coupling is unknown. Furthermore, while connexin36 (Cx36) is expressed by cones, the identity of the rod connexin has been controversial. We report that FACS-sorted rods and cones both express but no other connexins.

Connexin 57 is expressed by the axon terminal network of B-type horizontal cells in the rabbit retina.

In the rabbit retina there are two types of horizontal cell (HC). A-type HCs (AHC) are axonless and extensively coupled via connexin (Cx)50 gap junctions. The B-type HC (BHC) is axon-bearing; the somatic dendrites form a second network coupled by gap junctions while the axon terminals (ATs) form a third independent network in the outer plexiform layer (OPL).

Coupling between A-type horizontal cells is mediated by connexin 50 gap junctions in the rabbit retina.

There are many examples of neuronal coupling via gap junctions in the retina. Of these, perhaps the best known is the extensive coupling between horizontal cells. In the rabbit retina, there are two types of horizontal cells, A-type and B-type, both of which are independently coupled.

Direct synaptic connections between rods and OFF cone bipolar cells in the rabbit retina.

Mammalian retinal circuits are broadly divided into rod and cone pathways, responsible for dark- and light-adapted vision, respectively. The classic rod pathway employs a single type of rod bipolar cell, which synapses with AII amacrine cells. AII amacrine cells then pass the signal to ON and OFF cone bipolar cells, respectively.

Multiple neuronal connexins in the mammalian retina.

Gap junctions are abundant in the mammalian retina and many neuronal types form neural networks. Several different neuronal connexins have now been identified in the mammalian retina. Cx36 supports coupling in the AII amacrine cell network and is essential for processing rod signals.