Pych Jason C, Kim Munsoo, Gold Paul E
Department of Psychology, University of Illinois at Urbana-Champaign, 603 East Daniel Street, Champaign, IL 61820, USA.
Behav Brain Res. 2006 Feb 28;167(2):373-8. doi: 10.1016/j.bbr.2005.10.005. Epub 2005 Nov 11.
The present experiment tested the hypothesis that facilitation of striatal function with intra-striatal glucose injections would facilitate learning a striatum-dependent response maze and impair learning a hippocampus-dependent place maze. Food-deprived Sprague-Dawley male rats were trained to find food in a Y-maze. In the place version of the maze, rats were rewarded for learning to go to an arm located in a fixed location while in the response task rats were rewarded for consistently turning in the same direction at the choice point. Artificial cerebrospinal fluid (1 microL) containing either 0.7 nmol of glucose (control) or 20 nmol of glucose was injected bilaterally into the dorsal striatum immediately before training. The animals were trained to a criterion of 9/10 correct choices. In the place maze, glucose injections impaired learning, as measured by number of trials required to reach 9/10 correct. However, in the response task, glucose injections did not enhance learning. A subsequent experiment examined the effects of intra-striatal glucose injections on acquisition of the response task under two different visual cue conditions, addition of an intra-maze light cue that predicted the correct arm or with removal of most visual extramaze cues. Glucose again failed to facilitate acquisition of the response task under these conditions. These findings suggest that facilitation of striatal function via intra-striatal glucose injections is sufficient to impair place learning but not to enhance response learning, perhaps separating the neurochemical mechanisms for striatal involvement in impairment of place and enhancement of response learning.
向纹状体内注射葡萄糖促进纹状体功能，将有助于学习依赖纹状体的反应迷宫，并损害依赖海马体的位置迷宫的学习。将食物剥夺的斯普拉格-道利雄性大鼠训练在Y型迷宫中寻找食物。在迷宫的位置版本中，大鼠学会前往位于固定位置的臂部即可获得奖励，而在反应任务中，大鼠在选择点始终朝同一方向转弯即可获得奖励。在训练前，将含有0.7 nmol葡萄糖（对照）或20 nmol葡萄糖的人工脑脊液（1微升）双侧注入背侧纹状体。将动物训练至达到9/10正确选择的标准。在位置迷宫中，通过达到9/10正确所需的试验次数衡量，葡萄糖注射损害了学习。然而，在反应任务中，葡萄糖注射并未增强学习。随后的一项实验研究了在两种不同视觉线索条件下，向纹状体内注射葡萄糖对反应任务习得的影响，即添加预测正确臂部的迷宫内部灯光线索或去除大部分外部迷宫视觉线索。在这些条件下，葡萄糖再次未能促进反应任务的习得。这些发现表明，通过向纹状体内注射葡萄糖来促进纹状体功能足以损害位置学习，但不足以增强反应学习，这可能区分了纹状体参与位置损害和反应学习增强的神经化学机制。
