Bures J, Fenton A A, Kaminsky Y u, Wesierska M, Zahalka A
Institute of Physiology, Academy of Sciences, Prague, Czech Republic.
Neuropharmacology. 1998 Apr-May;37(4-5):689-99. doi: 10.1016/s0028-3908(98)00031-8.
Analysis of the neural mechanisms of place navigation requires isolation of the landmark dependent allocentric and self-motion related idiothetic orientation modes. To assess their importance, rats were trained on a rotating (360 degrees/min) arena to avoid foot shocks applied in either a room frame defined sector of the arena or an idiothetically defined region of the floor. Independence of the respective allocentric and idiothetic engrams was revealed by simultaneous avoidance of both locations. The possibility that idiothetic orientation was confounded by allocentric intramaze cues was examined in an apparatus consisting of an inner rotating disc surrounded by a stationary belt. As long as the rat was on the moving disc, position of the 60 degrees shock sector was stable on the disk but projected from it to different parts of the belt. When the rat moved to the belt the shock sector was now stable on the belt, but its projection to the disk travelled over its moving surface. The rat always found the shock sector in an idiothetically correct position but the mutual shifts of the disk and belt eliminated the utility of local cues like scent marks for the idiothetic solution of the task. Purely allocentric orientation was required in a place recognition task in which pressing a lever mounted on a rotating arena was rewarded only when the operandum moved through an allocentrically defined 60 degrees segment of its trajectory. Place recognition was manifest by increased bar pressing rates on approach to and inside the reward zone. These methods may reveal how hippocampal place cell activity correlates with both allocentric and idiothetic aspects of spatial orientation.
对位置导航神经机制的分析需要分离出依赖地标物的以自我为中心和与自我运动相关的非地标性定向模式。为评估它们的重要性，对大鼠进行训练，使其在一个旋转（360度/分钟）的实验场上避免受到施加在实验场房间框架定义区域或非地标性定义的地面区域的足部电击。通过同时避开这两个位置，揭示了各自以自我为中心和非地标性记忆痕迹的独立性。在一个由内部旋转圆盘和周围固定带组成的装置中，研究了非地标性定向是否被迷宫内部以自我为中心的线索混淆的可能性。只要大鼠在移动圆盘上，60度电击区域在圆盘上的位置是稳定的，但从圆盘投射到固定带的不同部分。当大鼠移动到固定带时，电击区域现在在固定带上是稳定的，但它投射到圆盘上的位置在圆盘移动表面上移动。大鼠总能在非地标性正确位置找到电击区域，但圆盘和固定带的相互移动消除了局部线索（如气味标记）对任务非地标性解决的作用。在一个位置识别任务中需要纯粹的以自我为中心的定向，在该任务中，只有当操作柄在以自我为中心定义的60度轨迹段移动时，按压安装在旋转实验场上的杠杆才会得到奖励。在接近奖励区和进入奖励区时，按压杠杆的速率增加表明了位置识别。这些方法可能揭示海马体位置细胞活动如何与空间定向的以自我为中心和非地标性方面相关联。
