Conserved and divergent development of brainstem vestibuloacoustic nuclei

Abstract

ABSTRACTVestibular function was established early in vertebrates and has remained, for the most part, unchanged. In contrast, tetrapods underwent independent evolutionary processes to solve the problem of hearing on land. Thus, the vestibuloacoustic nuclei of the hindbrain provide an ideal framework on which to address the participation of developmental processes to the evolution of neuronal circuits.We employed an electroporation strategy to unravel the contribution of dorsoventral and axial lineages to the development of the chick hindbrain vestibular and auditory nuclei. We compare the chick developmental map with recently stablished genetic fate-maps of the mouse hindbrain. Overall, we find considerable conservation of developmental origin for the vestibular nuclei. In contrast, auditory hindbrain development echoes the complex evolutionary history of the auditory system. In particular, we find that the developmental origin of a chick sound localisation circuit supports its emergence from an ancient vestibular network, unrelated to the analogous mammalian counterpart.