Zhang Yameng, Zhang Yan, Yu Hejuan, Yang Yamin, Li Weitao, Qian Zhiyu
Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, 211106, Nanjing, China.
Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, 211106, Nanjing, China.
Physiol Behav. 2017 Oct 1;179:135-142. doi: 10.1016/j.physbeh.2017.05.033. Epub 2017 Jun 1.
The dramatically increased use of electricity is raising major concerns as to the consequences of the interaction between electromagnetic field (EMF) and neurobiology. The aim of this study is to investigate the effects of magnetic field on working memory in the hippocampal region by analyzing local field potentials (LFPs) and spikes pattern in vivo. In present study, mice were exposed to EMF (50Hz, 1mT), static magnetic field (SMF, 1mT), or placed in the exposure tube but without EMF exposure (SHAM), respectively. During the exposure for 7 consecutive days, mice were subjected to perform working memory (WM) tasks in Y-maze, and multichannel electrophysiology signals from hippocampus of mice were recorded during the test, from which LFPs, spike firing rates, band power at different frequencies, and theta-gamma modulation index (MI) were analyzed in details. From our results, correct choice rate during WM task was found significantly decreased in EMF group after 3-day exposure, which was consistent with noticeable decline in firing rate. Starting from Day 3 after EMF exposure, the power of theta (4-12Hz) and gamma (LG, 30-60Hz) before reference point (RP) in Y-maze were also found to be descending, together with decrease of oscillatory activities of theta and gamma frequencies. The results indicated that MI between theta and gamma could play a significant role in modulating the spikes discharge and encoding WM. Therefore, the analysis of theta-gamma coupling and its oscillation strength may provide a new perspective for mechanistic investigation of EMF-induced WM deficits.
电力使用的急剧增加引发了人们对电磁场（EMF）与神经生物学相互作用后果的重大担忧。本研究的目的是通过分析体内局部场电位（LFP）和尖峰模式来研究磁场对海马区工作记忆的影响。在本研究中，小鼠分别暴露于电磁场（50Hz，1mT）、静磁场（SMF，1mT）或置于暴露管中但不暴露于电磁场（假手术组）。在连续7天的暴露期间，小鼠在Y迷宫中执行工作记忆（WM）任务，并在测试期间记录小鼠海马的多通道电生理信号，从中详细分析LFP、尖峰放电率、不同频率的频段功率以及theta-γ调制指数（MI）。从我们的结果来看，电磁场组在暴露3天后，WM任务期间的正确选择率显著下降，这与放电率的明显下降一致。从电磁场暴露后的第3天开始，还发现Y迷宫中参考点（RP）之前的theta（4 - 12Hz）和gamma（LG，30 - 60Hz）功率下降，同时theta和gamma频率的振荡活动减少。结果表明，theta和gamma之间的MI可能在调节尖峰放电和编码WM中起重要作用。因此，对theta-γ耦合及其振荡强度的分析可能为电磁场诱导的WM缺陷的机制研究提供新的视角。
