The name is absent

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saturating gain function at the synapse means that the bipolar cell output would be much
noisier for small signals due to the increased gain for these signals. Therefore, by filtering
signals in the rod network before they go through the synapse, the noise in the signals could
be reduced before they are amplified by the synapse.

Natural scenes tend to exhibit 1/f spectra or l∕f² power spectra [105, 11], which means
that the majority of the signal in natural images is contained low spatial frequency compo-
nents. These low spatial frequencies would be reproduced with better fidelity in a retina with
coupling than one without it. Although it can be argued, at least for higher animals such as
primates, that most of the information in visual scenes comes from higher frequency image
components, such as fine high contrast features like text and other symbols, the rod path-
ways are adapted to a different purpose. Instead, the rod pathway has evolved to operate in
dimly-lit low contrast environments, characteristic of natural environments in twilight and
in starlight.

Interestingly, Balboa and Grzywacz show that the power spectra of underwater images
exhibit anisotropy— they are different when measured in the horizontal vs vertical direction.
Salamanders spend the larval stage of their life in an aquatic environment, so it is possible
that their rod networks could have evolved to have their anisotropic coupling in order to
adapt to the spatial frequencies in their environment. Our results demonstrate significant
(Fisher F-test) variability in coupling conductances between different rod pairs, which could
have resulted from differing coupling conductances in the horizontal vs vertical direction.
Future work may evaluate whether such a difference does exist. If so, it would support our

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