电击回避训练前后快回避反应大鼠海马CA3区神经振荡的变化

Alteration of neural oscillations in hippocampal CA3 area in the fast avoidance response rat before and after electric shock avoidance training

本研究旨在探讨与动物空间辨别学习能力相关的神经振荡电活动及其改变。运用Y型迷宫电击回避训练方法,筛选出与空间认知能力相关的快回避反应组和普通回避反应组大鼠,无线遥测两组动物在电击回避实验前、后海马CA3区实时局部场电位(local field potential,LFP),分析与空间辨别和学习能力相关的神经振荡成分变化。结果显示,与普通回避反应组大鼠比较,电击回避训练前快回避反应组大鼠左侧海马CA3区LFP成分无显著差异,但电击回避训练后,右侧海马CA3区0~10 Hz和30~40 Hz电节律百分比显著增加(P<0.01或P<0.05);快速傅里叶变换显示,0~10 Hz频段百分比增加主要发生在θ波(3~7 Hz)频段,而30~40 Hz频段改变相当于γ1频段。进一步将两组大鼠训练前后的右侧CA3区神经振荡进行自身比较,结果显示训练后快回避反应组大鼠仅出现β波、β2(20~30 Hz)和γ1节律百分比增加,θ波节律百分比在训练前后无明显变化,而普通回避反应组大鼠训练前后比较显示,训练后右侧CA3区θ波节律百分比和大幅波(强度:+2.5^-2.5 db)显著减少(P<0.01)。本研究结果显示,快回避反应组大鼠电击回避训练后,右侧海马CA3区β2和γ1节律百分比增加,θ波节律百分比保持较高水平,这些改变可能与其较强的空间认知能力有关。

The purpose of the present study is to explore the relationship of spatial learning ability and specific electrical activities of neural oscillations in the rat. The fast and general avoidance response groups were selected on the basis of the animals＇ responses to the electric shock in Y type maze, and their local field potentials （LFPs） of hippocampal CA3 area were recorded by wireless telemetry before and after shock avoidance training, respectively. The components of neural oscillations related to spatial identifying and learning ability were analyzed. The results showed that, compared with the general avoidance response group, the fast avoidance response group did not show any differences of LFPs in hippocampal CA3 area before electric shock avoidance trial, but showed significantly increased percentages of 0-10 Hz and 30-40 Hz rhythm in fight hippocampal CA3 area after the shock avoidance training （P 〈 0.01 or P 〈 0.05）. Fast Fourier transform showed that percentage increase of 0-10 Hz band occurred mainly in θ （3-7 Hz） frequency, and 30-40 Hz frequency change was equivalent to the 71 band. Furthermore, compared with those before training, only the percentages of β, β2 （20-30 Hz） and 71 rhythm increased （P 〈 0.01 or P 〈 0.05） in fast avoidance response rats after training, while the θ rhythm percentage remained unchanged. In contrast, θ rhythm percentage and the large amplitude （intensity： ＋2.5 - -2.5 db） θ waves in right CA3 area of general avoidance response rats were significantly reduced after training （P 〈 0.01）. These results suggestthat the increased percentages of β2 and γ 1rhythm and high-level （unchanged） percentage of θ rhythm in the right hippocampus CA3 area might be related to strong spatial cognition ability of fast avoidance response rats.