How do new neural structures evolve and affect behavior?

Associate Professor, Zoology

My central interest is in the evolution of new neural structures and their role in behavior. My research focuses on changes in the olfactory system over the course of vertebrate evolution, and the origin and function of the accessory olfactory (vomeronasal) system in tetrapods. I work mostly with axolotls, Ambystoma mexicanum, a nonmetamorphosing salamander.

I am pursuing three interrelated lines of research in my laboratory. First, I am examining chemosensory-guided behavior in axolotls. This includes studies of chemical signalling in courtship and mating behavior, as well as attempts to isolate the compounds involved. Second, I am using electrophysiological techniques to examine the function and odor response properties of the olfactory and vomeronasal receptor cells in axolotls, with the goal of determining whether different portions of the olfactory and vomeronasal systems serve different biological functions. Third, I am examining the developmental origin of the olfactory and vomeronasal organs and their targets in the central nervous system, with a view to understanding the developmental changes involved in the evolutionary origin of the vomeronasal system.

I have taken a similar approach to studying the origin and function of the terminal nerve, a mysterious anterior cranial nerve that is present only in jawed vertebrates. The terminal nerve appears to serve a neuromodulatory function, and may be involved in regulating olfactory sensitivity and reproductive behavior. I hope that by taking a broad, integrative approach to these problems, I will gain a better understanding of how new neural structures arise in evolution, and how they get incorporated into an existing nervous system to mediate behavior.

Selected Publications

Eisthen, H.L. 1992. Phylogeny of the vomeronasal system and of receptor cell types in the olfactory and vomeronasal epithelia of vertebrates. Microscopy Research and Technique 23:1-21.

Eisthen, H.L., D.R. Sengelaub, D.M. Schroeder and J.R. Alberts. 1994. Anatomy and forebrain projections of the olfactory and vomeronasal organs in axolotls (Ambystoma mexicanum). Brain, Behavior and Evolution 44:108-124.

Eisthen, H.L. 1997. Evolution of vertebrate olfactory systems. Brain, Behavior and Evolution 50:222-233.