The ampullary electroreceptors of certain sh were shown to exhibit awesome sensitivity to low-frequency electric elds. It is a considerable challenge to disco ver how this ability to resolve signals out of noise is accomplished. No doubt it is due in large part to the fact that the AoLs are found in three-dimensional arrays over the heads and bodies of the sh that use them. Thus, the sh can use some form of spatiotemporal averaging to achieve their great sensitivity in prey location. How the sh processes the spik e signals from individual AoL axons in its CNS remains to be described.
A WEF has an electric organ that produces an ac eld of constant frequenc y around its body. Distortions in this eld caused by nearby objects having conductivities different from the water are sensed and used by the sh for guidance in murk y water. The knollenorgan receptors, like the AoL, are arranged in arrays. By using an ac eld, in principle, the sh can use some kind of synchronous detection to obtain an impro ved resolution and SNR. (Synchronous detection is used in the well-known lock-in ampli-ers.) Again, neuroethologists and neurophysiologists are just beginning to understand the CNS mechanisms underlying the navigation skills of WEF.
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