Dr. Northcutt is a leader in comparative vertebrate neurobiology. The Northcutt laboratory conducts research work in three major areas: comparative neurobiology of vertebrate forebrain organization and cranial nerves, development and evolution of the lateral line system, and development of the gustatory system.
Comparative vertebrate neurobiology: The Northcutt laboratory has continued to generate new data on the immunohistochemistry and connections of the forebrain and cranial nerves of phylogenetically important taxa. These data have resulted in new interpretations of the evolution of both the forebrain and cranial nerves. Much of the information has already been incorporated into standard textbooks of comparative vertebrate anatomy (Kardong, 1999, WC Brown Publishers) and comparative vertebrate neuroanatomy (Butler and Hodos, 1996, Wiley-Liss; and Nieuwenhuys et al., 1998, Springer-Verlag). Dr. Northcutt is currently writing a textbook on the evolution of vertebrate brains (Oxford University Press), in which he hopes to summarize more than 30 years of research activity.
Lateral line system: Dr. Northcutt and colleagues continue long-term investigations into the organization and development of the lateral line system of an aquatic salamander that retains a primitive pattern of mechanoreceptive organs, and the channel catfish, which has re-evolved electroreceptive organs. This salamander was specifically chosen in order to develop a detailed model of how receptors and neural crest are involved in the genesis of the lateral line system, and to explore the role of developmental changes in the evolution of this vertebrate sensory system. Extensive studies have allowed Dr. Northcutt to characterize this model, and generate a hypothesis regarding the exact number and developmental fate of sensory receptors and their role in the evolution of the vertebrate head.
One of the most exciting aspects of this work was the demonstration that Hox genes appear to specify the lateral line sensory receptor, and that the generation of electroreceptive organs can be suppressed by exposing early embryos to retinoic acid, which re-patterns Hox gene expression in these receptors. Development of the gustatory system: A third major line of ongoing investigation has been on the development of the gustatory system. An understanding of this sensory system has lagged far behind that of other sensory systems, primarily due to the lack of a good experimental model. For this reason most ideas regarding the development and innervation of taste buds have been derived from regeneration studies. The Northcutt group has developed an amphibian model, which circumvents most of the problems associated with experimental manipulation and culture of mammalian embryonic tissues. For the first time, the group was able to establish the embryonic origin of vertebrate taste buds, and to demonstrate that taste bud development does not require neural induction, thus negating the most widely accepted hypothesis of taste bud induction.
The laboratory has continued to examine the possible role of other embryonic tissues, such as neural crest and/or mesoderm, in the induction of taste buds and demonstrated that these tissues do not play a role in the induction of taste buds and that pharyngeal endoderm and taste bud stem cells must be specified during gastrulation. This work led to the discovery that Hox genes appear to be involved in the antero-posterior patterning of the pharynx.
Dr. Northcutt provides formal courses at the graduate level as well as individual instruction. He co-organized a course on the origin and evolution of vertebrates. Until recently, he served as Editor-in-Chief of the journal Brain, Behavior and Evolution. He continues to serve as a member of the Editorial Boards of the Journal of Comparative Neurology, Journal of Morphology, Visual Neuroscience, and Zoologische Reike. He is a frequent reviewer for such premier scientific journals as Science, Nature, and Proceedings of the National Academy of Sciences.