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

点击翻译按钮获取中文摘要

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.