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voltage distribution in the bipolar cell layer [6]. Deans et al. showed that the gap junction
protein connexin-36 is expressed between mouse rods [29], highlighting it as a candidate
for rod-rod coupling. Zhang and Wu recorded from salamander rods in the slice prepa-
ration and measured a coupling resistance of 2 GΩ. They also showed immunostaining for
connexin-35/36 between these rods, implicating connexin-36 as the determinant of rod-rod
coupling.
While there have been at least two separate estimates of the coupling resistance between
salamander rods, the reported values are very different from one another. This may be due
to drawbacks in the experimental techniques used by each of the reports. The 300 MΩ esti-
mate by Attwell and Wilson was performed using sharp electrodes, which could have com-
promised the cell membrane, and the 2000 MΩ estimate was performed in retinal slices,
where the connections between rods could have been damaged. While it is well known that
rod-rod coupling reduces noise in the network, the conditions under which this translates
to a favorable signal-to-noise ratio are unclear. In chapter 5, this thesis attempts to address
these deficiencies.