FACULTY

My laboratory focuses on the development and evolution of vertebrate nervous systems, with particular emphasis on sensory systems. Numerous approaches are employed, including descriptive and experimental embryology, immunohistochemistry, and neuroanatomical tracing techniques, and all data are analyzed within the framework of modern evolutionary (cladistic) theory.

FOREBRAIN ORGANIZATION IN ANAMNIOTIC VERTEBRATES. Understanding the organization and evolution of the cerebral hemispheres of fishes, amphibians, and reptiles represents one major form of the research presently underway in my laboratory. To this end telencephalic and diencephalic neural centers in various species are described. The modulators and transmitters, as well as the connections, are determined in order to identify the same centers in various species. These data are then analyzed using current phylogenetic methods to determine the nature of neural evolution.

ORGANIZATION AND DEVELOPMENT OF LATERAL LINE SYSTEM. Most fishes and many amphibians possess an extensive sensory system comprising electroreceptors and mechanoreceptors which are composed of hair cells and comparable to the receptors within the inner ear of mammals and other vertebrates. The lateral line system is of interest for two reasons: 1) it constitutes one of the major sensory systems of many vertebrates and plays a number of critical roles in their behavior; and 2) it can be used as a model to understand many aspects of the development of the inner ear of mammals. Current studies on this system involve describing the structure of these receptors with scanning electron microscopy, mapping their distribution over the bodies of phylogeneticallly important species, and experimentally determining the innervation of these receptors and their representation in the central nervous system. Developmental and molecular studies are also underway in order to reveal what genes and inductive molecules are necessary for the development and alteration of these receptors.

DEVELOPMENT OF TASTE BUDS. All vertebrates possess a series of multicellular chemosensory receptors termed taste buds. Until recently, the embryonic source of taste buds was unknown, as were the sensory neurons that innervate these receptors. My laboratory has recently demonstrated that taste buds arise from endoderm, and we are now attempting to understand how the pharyngeal endoderm is patterned to form taste buds by applying a number of cell culture and molecular techniques. It is possible that the sensory neurons that innervate taste buds arise from one of two embryonic tissues: epibranchial placodes or neural crest. Intracellular marking and transplantation experiments are presently being conducted on these embryonic tissues to determine which, if either, gives rise to neurons. We are also extremely interested in the chemical clues used by the developing neurons to identify their targets.