Learning, Recognition and Memory of Place, and Neural Network in Hippocampus

记录大鼠海马复合体-脉冲活动，研究地点-奖赏关联学习的神经元机制。当大鼠进入一个随机设置的奖励场所，或进入两个特定的奖励场所，一个在场所场内，一个在场所场外时，诱导对下丘脑外侧的颅内自我刺激作为奖励。实验1:8只随机漫游训练动物的5个CA1神经元在训练前表现出明显的空间依赖性。在空间导航任务的成功学习中，1获得了位置依赖性，4增加了位置依赖性。这些结果表明，海马体神经元的位置依赖在一定程度上是位置-奖励关联学习的结果。实验二：本实验旨在研究什么信息在位置神经元中编码。对复杂脉冲发射模式的详细分析表明，运动轨迹的转向与复杂脉冲序列的最后一个脉冲的时间之间存在相关性。这表明一些海马体神经元可能将信息编码到位置场的预定目标。实验三：研究大鼠海马CA1区位置神经元活动与Schaffer侧枝高频刺激的相互作用。高频刺激对随机漫游和空间导航功能均有损害。刺激后海马活动被抑制，位置场消失。1小时内，神经元活动和位置场恢复到对照水平。但是，位置字段与对照不同。这表明强烈的人工电刺激可能会中断空间原有的信息存储。

Rat hippocampal complex-spike activity was recorded to study neuronal mechanisms of place-reward association learning. Intracranial self-stimulation to lateral hypothalamus as a reward was induced when the rat entered an random-set rewarding place, or entered two specific rewarding places, one in and one outside of the place field.Experiment 1 : Of 8 animals well-trained under the random wandering, but not the spatial navigation, 5 CA1 hippocampal neurons showed significant spatial dependency before training.1 acquired and 4 increased place dependency at the successful learning of spatial navigation task. These suggest that place dependency of hippocampal neurons is partly a result of place-reward association learning.Experiment 2 : This experiment was carried out to study what information encodes in the place neurons. Detailed analysis of complex-spike firing patterns shows a correlate between turning of trajectory of the movement and the timing of last spike of the complex-spike trains. This suggests that some hippocampal neurons might encode an information to the intended target in the place field.Experiment 3 : Interaction between place neuron activity and high frequency stimulation of Schaffer collateral was studied in rat hippocampal CA1. The high frequency stimulation impaired both random wandering and spatial navigation spatial tasks. The hippocampal activity was suppressed and the place field disappeared just after the stimulation.Within a hour, the neuronal activity and place field was recovered at the control level. However, the place fields were different from the control. These suggest that strong artificial electrical stimulation might interrupt original information storage of space.