TRAINING IN A NOVEL ENVIRONMENT IMPROVES THE APPETITIVE LEARNING-PERFORMANCE OF THE SNAIL, LYMNAEA-STAGNALIS

The effect of novelty, an environmental background variable affecting feeding and appetitive learning performance, was examined in a behavio ral study of the pond snail Lymnaea stagnalis. Transfer of snails into a novel aquatic environment (clean water) evoked exploratory behavior which manifested itself in an increased number of spontaneous rasping movements of the mouth over the second to fifth minute after exposure to the novel environment. The intensity of this behavior was much wea ker in a familiar environment (used water from the home tank). Similar ly, sucrose-induced feeding rates were highest when the snails were gi ven the sucrose stimulus in a novel environment. The effectiveness of appetitive conditioning using tactile stimulus paired with food (Kemen es and Benjamin, 1989a) improved when the snails were subjected to con ditioning in a novel environment. Satiety, an internal variable, suppr essed the stimulating effects of the novel environment on the spontane ous, unconditioned, and conditioned feeding alike. After training in t he novel environment, the conditioned response was retained for up to 12 days and thus provided a robust behavioral paradigm for the extensi on of the analysis to the neurophysiological mechanisms of factors aff ecting appetitive learning in molluscs. (C) l994 Academic Press,Inc.