Receptor position, not nerve branch, determines electroreceptor somatotopy in the gymnotiform fish (Apteronotus leptorhynchus).

The supraorbital (SO) nerve branch of some weakly electric teleosts innervates electroreceptors on the entire rostral snout and therefore excludes the infraorbital (IO) branch. A ventral twig of SO innervates the ventral snout (normally IO territory) and projects into the electroreceptive lateral line lobe in an IO pattern. This suggests that afferents to adjacent snout receptors can take widely divergent pathways (different nerve branches) to the electrosensory lateral line lobe (ELL) yet retain somatotopy centrally. We conclude: (1) that there is intrabranch somatotopy within these nerves, and (2) that receptor position, not nerve branch, determines ELL somatotopy.