スコポラミン慢性投与によるラットの時間弁別の感度の低下
2001 年 71 巻 6 号 p. 454-461
詳細
2001 年 71 巻 6 号 p. 454-461
The purpose of this paper is to clarify whether chronic scopolamine injection of two different doses have different effects on temporal discrimination behaviors and whether a central cholinergic blockade alters memory of stimulus duration. After performances were stabilized in peak interval (PI) 20 s training with saline injection, rats were injected scopolamine hydrobromide 0.5 or 0.15mg/kg (n=9 or 10, respectively) intraperitoneally 15 min before training for 15 days. In 0.5mg/kg group, (a) values of discrimination index (DI) consistently decreased, (b) response rates during ITI increased, and (c) peak times were shortened with the scopolamine treatments. The second effect was attenuated as trainings with scopolamine were progressed. In 0.15mg/kg group, there was no notable effect. Against our expectation, we could not have any evidence that scopolamine changed the time value stored in memory. We consider these results that the sensitivity of temporal discrimination was attenuated with scopolamine. These results were discussed in relation to the central cholinergic systems, especially the prefrontal cortex.
