Organization and Reorganization of Pattern Generators: A Comparative approach. Only in recent years have we begun to understand in reasonable detail how specific neural circuitry mediates any given behavior. A fundamental question that is difficult to directly address is: "How do behaviors co-evolve with the neural circuitry that mediates the behaviors?" This comparative study will begin to examine this general question by exploiting invertebrate feeding systems. Many invertebrates have neurons with unique identities. These identifiable neurons have morphological and physiological characteristics, and interconnections with other identifiable neurons, that are replicated in each individual of a species. As specification occurs some of the properties and interconnections of some of these identifiable neurons will diverge, whereas others will remain unchanged. Many distantly related gastropods (i.e. different subclasses) have relatively similar feeding behaviors. In contrast many closely related gastropods have radiated into diverse ecological niches with corresponding diversification of feeding apparatuses and behaviors. This study exploits data on the circuitry underlying similar feeding and ingestive behaviors in the distantly related opisthobranch sea hare, Aplysia californica, and pulmonate pond snail, Helisoma trivolvis. Similarities and differences in the neural control of feeding in these animals will be experimentally analyzed. These data will provide a baseline for examining the changes that have occurred in neural circuitry devoted to oral behaviors in closely related but ecologically diverse gastropods as the oral behaviors and morphological feeding apparatuses have evolved.
