Influence of Training Strength on Long-Term Retention of a Conditioned Saccharin Aversion in Rats
The retention of a conditioned taste aversion was tested under two training strengths, over a 14-day period. On training day, water was replaced by a 0.1 % saccharin solution (novel taste). Thirty minutes later, the rats received an i.p. injection of saline or were poisoned with LiCl (110 mg/kg). Fourteen independent groups (7 saline and 7 LiCl groups) were tested for retention either 1, 2, 3, 4, 7, 10 or 14 days following training. On retention day, each rat was submitted to a two-bottle choice procedure (saccharin vs water). Preference for saccharin was evaluated through the following ratio: 100 × (saccharin intake/total intake). When 30 minutes elapsed between saccharin (CS) and LiCl (US), the animals developed a significant aversion thereafter (p at least < 0.05): the grand mean saccharin preference index was 5.3 % within the LiCl groups and 64,4 % within the saline groups. No significant fluctuations in the magnitude of aversion appeared between different retention intervals. A previous work (Biederman et al., 1974) showed that memory of a conditioned saccharin aversion followed a U-shaped function. However, the authors used a one-bottle procedure which does not seem to be the most appropriate to investigate the memory of aversion. In a second experiment, our general procedure was employed except that a 3-hour CS-US delay was used in order to decrease the strength of training.