Investigation of the Neurobehavioral Mechanisms for Reward Reduction via Using the Procedure of Successive Contrast

• Main Authors: Feng-jung, Chuang, 莊豐榮
• Other Authors: 廖瑞銘
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/01520126173982790961

碩士 === 國立政治大學 === 心理學系 === 89 === Abstract The present study successive negative contrast (SNC) investigated what psychological processes and neural systems were involved in the comparison behavior. The SNC effect induced by rat’s licking different concentrations of sucrose solution was established and the effect in diazepam (a benzodiazepine agonist) as well as experimental manipulation of food deprivation were observed. In Experiment 1, the SNC effect was induced when the sucrose solution shifted from 32% down to 4%.This effect was observed across the consecutive 4 post-shift days in the free-feeding subjects; however, such effect was gradually diminished in the food-deprived subjects. Experiment 2 manipulated the food deprivation states to study how the hunger drive would affect the SNC. The results revealed that the food-deprived subjects in the pre-shift session show the SNC effect only on the second day of post-shift session with food supplied freely. However, the SNC effects were observed in the consecutive four post-shift days in the subject with free-feeding in the pre-shift session but was then altered into the state of food-deprivation. In Experiment 3, the SNC effect was attenuated by systemic injection of diazepam with the observation of the reduced licking suppression on the second post-shift day. In Experiment 4, with similar manipulation of food supply, diazepam was found to enhance the sucrose licking in addition to its reduction of the SNC effect. The central loci for diazepam to attenuate the SNC effect were investigated in Experiment 5. Although the SNC effect was attenuated by diazepam infused into the medial amygdala or the dorsal hippocampus, the time courses to observe such reduction were different for drug infused into both sites. The study indicates that（a）the SNC effect on licking can be reliably induced by decreasing the sucrose concentration,（b）such effect is attenuated by diazepam via central neural mechanisms. However, further research is needed to determine whether the attenuation of SNC by diazepam is based on the anxiety suppression or appetite enhancement process. Key Words: comparison behavior, motivation, emotion, limbic systems, anxiolytic