| Summary: | 碩士 === 國立中正大學 === 心理學研究所 === 90 === The amygdala was blocked with lidocaine, a local anesthetic, to study its role in the acquisition of conditioned taste aversion (CTA). This nucleus has been shown to mediate the learning and memory of CTA with the lesion method. However, the lesion caused permanent damage, rendering identification of the substages (encoding, short-term memory trace, conditioning, retrieval) of CTA difficult. The blockade with local anesthetics in the amygdala was functional and reversible and might be useful to identify which substage was subserved by the nuclei. Rats were given 10 min access to novel tastants (0.1% saccharin solution in Experiments 1 & 2a, 0.2% in Experiments 3b & 4a, or 25% grape juice in Experiments 2b, 3a, & 4b). And, at various time points during the CS-US delay (120 min in Experiment 1, 60 min in Experiments 2a-4b, or 30 min in Experiment 2a & 2b), the rats were administered with 0.15M LiCl (20 ml/kg, i.p.). Lidocaine was infused into the amygdala during CS-US interval or after LiCl injection. The CTA was then tested 2 days later. The results showed that lidocaine slightly attenuated the CTA when infused during the CS-US interval (Experiment 1), or 15 min or 30 min after LiCl injection (Experiments 3a, 3b. 4a, & 4b). Further, the attenuation was greater when the CTA was trained with a 30-min delay than that with a 60-min delay. The attenuation was also expressed on the day between the conditioning and the testing day. Lidocaine infusion into the amygdala was found to cause a generalization of the CTA to water.
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