BLOCKING AND AUGMENTATION IN PREWEANLING RATS: ROLE OF THE SENSORY MODALITY AND TEMPORAL CONTIGUITY OF THE TRAINING CUES

ARIAS, C.; GAZTAÑAGA, M; CHOTRO, M. G.

Congreso; International society for Developmental Psychobiology; 2012

International society for Developmental Psychobiology

The Kamins blocking effect is a cue competition phenomenon in which a previously conditioned cue (CS1) blocks conditioning of another cue (CS2) when both cues are trained in compound. Blocking is dependent on the activity of the dorsal hippocampus, a brain structure that seems not to be fully functional until the rats weaning period. In the present study we explored the performance of preweanling rats in a blocking procedure using a conditioned taste aversion paradigm, and whether this effect is modulated by the temporal contiguity and the sensory modality of the training cues. In this series of experiments preweanling rats received two training sessions (postnatal days 14 and 15) in which a CS1 was followed by a LiCl injection. In phase two (postnatal day 16) the CS1 was presented together with a CS2 before LiCl administration. The training stimuli were lemon odor and saccharin, counterbalanced. Results showed that a previously conditioned odor completely blocked conditioning of a taste, while the opposite phenomenon (i.e. augmentation) was observed when the CS1 was saccharin and the CS2 was lemon odor. Blocking was attenuated when both cues were presented successively at conditioning. These results demonstrate that blocking and augmentation can be observed in the infant rat. The capability of a stimulus to block or enhance conditioning of another stimulus is dependent on its sensory quality.