Meeting Abstract

P2.21  Jan. 5  Wood Frog Tadpoles Develop Conditioned Aversions to Novel Flavors SKIBINSKI, Adam P.*; CRESPI, Erica J.; Vassar College; Vassar College adskibinski@vassar.edu

Conditioned taste aversion (CTA) is a mode of learning in which animals associate a novel flavor stimulus with an unpleasant or toxic response. A central question about CTA concerns its relationship to neural development and, in particular, how early in development animals can display CTA. Amphibians provide an excellent way to answer this question because they can be experimentally manipulated at all developmental stages and many neural controls of behaviors are similar to those of mammals. We induced CTA in larvae of the wood frog, Rana sylvatica, by exposing them to a novel flavor (raspberry gelatin or vanilla) then injecting them with a toxic agent, lithium chloride (LiCl) at three doses: 1.25, 2.50, and 3.75 mg/animal. A sample of tadpoles that were exposed to the novel flavors but not injected served as a control group. The exposure-injection pairings were repeated three times, and feeding behavior was observed throughout this period. Compared with uninjected controls, LiCl-injected tadpoles ate significantly less of both flavored and unflavored food during the initial treatment period (ANOVA, P < 0.05), indicating that the LiCl injections likely caused a stressful condition that may be associated with the novel flavor. After a two-week recovery period, LiCl-injected tadpoles ate unflavored food on a par with controls, but showed a significant decrease in feeding relative to controls when given flavored food (t-test, P = 0.05). These data suggest that wood frogs can indeed learn CTA as early as the tadpole stage, and that the neural mechanisms are in place very early in vertebrate development. Future experiments are needed to replicate this result and to determine whether the CTA will persist even once the animals have metamorphosed into their adult forms.