Recovery-from-extinction effects in an anuran amphibian: renewal effect, but no reinstatement

ABA, AAB and ABC renewal with Pavlovian Conditioning of Tentacle Lowering procedure in the snail Cornu aspersum

This study assesses the recovery of the conditioned response (CR) due to a contextual change (renewal effect) in the Cornu aspersum, using the appetitive Pavlovian Conditioning of Tentacle Lowering procedure. Snails experienced an odorous conditioned stimulus (CS) paired with food (conditioning), followed by the exposition to the CS without any consequence (extinction). Then, they were exposed to the CS in a different context from the extinction one (renewal test). The contexts were three types of illumination. In Experiment 1a, the conditioning was performed in context A, the extinction was conducted in context B and the renewal test was performed in context A. For Experiment 1b, the conditioning and extinction were conducted in context A and renewal was performed in context B. In Experiment 1c, three dissimilar contexts were used for each experimental phase: context A for the conditioning, context B for the extinction and context C for the renewal. In Experiment 2, the renewal magnitude was compared among the three paradigms (ABA, AAB and ABC). Experiments 1a, 1b and 1c showed a recovery of the CR when subjects experienced a contextual change and Experiment 2 showed equivalent levels of renewal in the three paradigms. Learning processes and theories involved are discussed.

Context specificity of latent inhibition in the snail Cornu aspersum

The present study was conducted to assess the context specificity of latent inhibition (LI) in the snail Cornu aspersum, using the appetitive Pavlovian Conditioning procedure of tentacle lowering. Snails experienced an odorous conditioned stimulus (CS) without any consequence before being conditioned with food. The conditioned stimulus preexposure occurred in the same context than the conditioning and the test context or in the different context. The study was performed in two replicas in which the photoperiod was defined by level of illumination and time of day (circadian replica) or was defined only by light (light replica). Both replicas showed that the CS preexposure in the same context as conditioning produced a delay in the acquisition of the conditioned response (CR). However, when the CS preexposure took place in a different context than the conditioning context, an equivalent level of CR as that observed in controls without preexposition to CS was shown. These results are congruent with context specificity of LI and they provide the first evidence of this phenomenon in terrestrial mollusks. Learning processes and theories involved in this phenomenon are also debated in the paper.