LAtent inhibition and facilitation of conditioned taste aversion in infant rats

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

New Orleans

Congreso; International society for Developmental Psychobiology; 2012

International society for Developmental Psychobiology

In adults, stimulus preexposure generally induces a latent inhibition effect. Early in ontogeny, however, this effect is rarely found and facilitation of conditioning is more often observed. The effects of stimulus preexposure on conditioned taste aversion (CTA) were investigated in 2-week-old rats. On postnatal day (PD) 13 pups received 0, 1 or 3 preexposure trials to saccharin. After this, all pups received the conditioned stimulus (CS) saccharin followed by the unconditioned stimulus (US): saline, 0.15M LiCl, or 0.30M LiCl. On PD14, conditioning was repeated and saccharin intake was registered. On PD15 saccharin consumption was again tested. After one conditioning trial and without preexposure only the strong US induced CTA. With one preexposure however, CTAwas observed with both doses. Three preexposure trials reduced CTA observed with the highest dose, but not the aversion observed with the low dose. After two conditioning trials, all conditioned groups showed CTA regardless the amount of preexposure and the US intensity. In conclusion, stimulus preexposure can either facilitate conditioning or induce latent inhibition in infant rats, depending on the amount of stimulus preexposure and the intensity of the US. This early learning does not generalize to other tastes.