Klement D, Bures J
Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic.
Proc Natl Acad Sci U S A. 2000 Mar 14;97(6):2946-51. doi: 10.1073/pnas.040576197.
Spatial memory of animals is usually tested in navigation tasks that do not allow recognition and recall processes to be separated from the mechanisms of goal-directed locomotion. In the present study, place recognition was examined in rats (n = 7) confined in an operant chamber mounted on the periphery of a slowly rotating disk (diameter 1 m, angular velocity 9 degrees /s). The animals were passively transported over a circular trajectory and were rewarded for bar pressing when they passed across a 60 degrees -wide segment of the path. This segment was recognizable with reference to room landmarks visible from the operant box. Responding defined in the coordinate system of the room increased when the chamber entered the 60 degrees -wide approach zone, culminated at the entrance into the reward sector, was decreased inside it by eating the available reward, and rapidly declined to zero at the exit from this zone. When reward was discontinued, the skewed response distribution changed into a symmetric one with a maximum in the center of the reward sector. With advancing extinction, the response peak in the reward sector decreased in most rats proportionally to the overall decline of bar pressing. The rewarded and nonrewarded response patterns indicate that passively transported rats can recognize their position in the environment with an accuracy comparable to that of actively navigating animals and that location-driven operant responding can serve as a useful tool in the analysis of the underlying neural mechanisms.
动物的空间记忆通常在导航任务中进行测试，这些任务不允许将识别和回忆过程与目标导向运动的机制分开。在本研究中，对被限制在安装在缓慢旋转圆盘（直径1米，角速度9度/秒）周边的操作性实验箱中的大鼠（n = 7）进行了位置识别测试。动物被被动地沿着圆形轨迹运输，当它们经过路径上60度宽的一段时，按压杠杆会得到奖励。这段路径可以根据从操作性实验箱中可见的房间地标来识别。当实验箱进入60度宽的接近区域时，在房间坐标系中定义的反应增加，在进入奖励区域时达到峰值，在奖励区域内通过吃掉可得奖励而减少，并在离开该区域时迅速降至零。当奖励停止时，偏态的反应分布变为对称分布，在奖励区域中心达到最大值。随着消退的推进，大多数大鼠奖励区域内的反应峰值与按压杠杆的总体下降成比例下降。有奖励和无奖励的反应模式表明，被动运输的大鼠能够以与主动导航动物相当的精度识别其在环境中的位置，并且位置驱动的操作性反应可以作为分析潜在神经机制的有用工具。
