Differential Conditioning to a Compound Stimulus and its Components in the Terrestrial Mollusc Limax maximus

The neuronal mechanism of associative learning and memory storage operating in the central nervous system of the terrestrial mollusc Limax maximus has been modeled as a computer simulation called LIMAX (Gelperin, J. J. Hopfield, & Tank, 1985). One test of the LIMAX model is to determine whether Limax can learn to avoid a compound stimulus composed of the mixture of two innately attractive odors without simultaneously learning an aversion to the individual odors comprising the mixture. We found that Limax can learn a strong aversion to odor A + B while odor A and odor B remain strongly attractive when presented individually. This result led us to reexamine the sensory coding scheme used in the LIMAX model to represent stimulus mixtures, and it suggests neurophysiological experiments to examine the actual chemosensory coding scheme used by Limax.