Effects Of Extremely Low Frequency Electromagnetic Fields On Network Connection Of Local Field Potentials

With the wide application of electrical equipment and the increasingly complex electromagnetic environment in people’s daily life,people are more and more exposed to the electromagnetic environment.More and more attention has been paid to the potential impact of electromagnetic field on human health.Studies have shown that long-term exposure to low-frequency electromagnetic fields may have negative effects on neurological system functions.Power frequency electromagnetic field is the most typical extremely low frequency electromagnetic field.From the perspective of neural information network connection,the effects of electromagnetic fields on the nervous system especially on the cognitive function of the brain have become an important issue in the field of electromagnetic biological effects.The SD rats were used as subjects to prepare the model of power frequency electromagnetic field.An array of microelectrodes is implanted in the prefrontal cortex of rats using multi-channel neural signal recording technology in vivo.The LFPs singal of rats is collected during the working memory task in the T maze.And then the time-frequency analysis and Granger causality analysis,combined with the result of the rats behavior,is applied to explore the effect of power frequency electromagnetic field on LFPs signal network connection in working memory of rats.The main research contents is as follows:1.Rat model preparation and microelectrode array implantation.The model Ⅰand model Ⅱ group of rats were exposed to 50 Hz,2 m T power frequency electromagnetic field environment for 24 days and 48 days respectively.The control group of rats were no power frequency electromagnetic field exposure.The microelectrode array was implanted into the prefrontal cortex of three groups’ rats respectively.2.The data in working memory were acquired.Neural electrical signals of the prefrontal cortex of rats were collected and recorded by the multi-channel microelectrode neural signal recording system when rats performed T maze working memory task,and then the 16-channel LFPs signals were acquired through low pass filtering and preprocessing.3.The behavioral results of working memory task were compared and analyzed.The days of learning T maze working memory task,and the correct rate under the same training times,were counted,and the behavioral data of rats in different groups were statistically analyzed.4.LFPs time-frequency energy and network connection characteristics were analyzed.Short-time Fourier transform was used to analyze LFPs signals to compare the time-frequency distribution and dynamic energy changes of rats in different groups.The LFPs signal was analyzed by Granger causality network,and the average DTF,network connection density and global efficiency of LFPs signal in rats of different groups were calculated,and the statistical comparison analysis was conducted.The research showed that after exposure to the power frequency electromagnetic field,the required days and the training times for rats to learn T maze working memory task increased,and the θ and γ frequency energy of LFPs singal of rats during working memory task decreased.And the average DTF,the connection density and the global efficiency of network connection characteristic parameters were also reduced.And further with the increase of power frequency electromagnetic field exposure time,time-frequency energy and brain network parameters were declining.The above results showed that exposure to the power frequency electromagnetic field maybe have affected on the network connection characteristics of LFPs signals in the prefrontal cortex of rats,resulted in the reduction of neural information transmission efficiency and network connection density.