The Brains of Cartilaginous Fishes

In this chapter we present a modern interpretation of the regional organization of the chondrichthyan brain mainly based on updated genoarchitectonic, neurochemical, and, in a lesser extent, hodological data in the brain of the catshark Scyliorhinus canicula . Particularly, the comparative analysis of the spatiotemporal expression patterns of developmental genes using this shark species as representative of basal gnathostomes has proved to be essential for recognizing the functional regionalization of the chondrichthyan brain, identifying common and divergent patterns in the specification of brain subdivisions, and, eventually, better understanding the diversity of vertebrate nervous systems.