Effects Of High-frequency Repetitivef Transcranial Magnetic Stimulation On Neural Signal Coordinate Encoding Of Working Memory In Rats

Repetitive transcranial magnetic stimulation(r TMS)technology is a non-invasive neuromodulation therapy that has been widely used in the field of neurological rehabilitation.Working memory is the basis of brain cognitive function and one of the important indicators of nervous system function.Most current studies have shown that high-frequency r TMS is more effective for improving working memory function.However,the neural regulation mechanism of working memory under different high frequencies of r TMS is not yet clear.This thesis intends to research the effect of different high-frequency r TMS on the coding activity of local field potentials(LFPs)and spike during working memory from the perspective of neural coding activities using in vivo multichannel recording technology.The main research contents include:1.Model preparation and data acquisition.First,high-frequency r TMS rat model was prepared and microelectrode array implantation was performed.Wistar rats were randomly divided into four groups.For model groups,the rats were stimulated by 5 Hz,10 Hz,and 15 Hz r TMS seperately.Rats in control group were not accepted r TMS.Then microelectrode arrays were implanted into the prefrontal cortex of each group of rats by surgery.After implantation of electrodes,rats in each group performed T-maze working memory task,and simultaneously 16-channel raw data were recorded.Then 16-channel LFPs signals and spike signals were acquired through signal preprocessing.2.Comparative analysis of working memory behavior.The T-maze working memory task of rat were designed and conducted.The correct rate of T-maze working memory task of each group were calculated,and counted the number of days to reach the working memory behavioral correctness standard.The results showed that r TMS can reduce the required days for rats to reach the standard of working memory correct rate.3.Time-frequency analysis of LFPs.Time-frequency energy analysis was performed on LFPs signals based on short-time Fourier transform,and the time-frequency distribution and average energy of LFPs in working memory of different groups of rats were compared.The results showed that the θ and γ frequency energy of LFPs singal in high-frequency groups during working memory task are higher than that in control group.4.Coordinate encoding of LFPs θ-γ band were analyzed.Based on the analysis of the modulation index(MI)value of the phase-amplitude coupling,the changes in the intensity of the coordinate encoding of LFPs signals in the θ-γ band of different groups were compared.The results showed that high-frequency r TMS increases the intensity of the coordinate encoding of the θ-γ band of the LFPs signal,and to a certain extent,the higher r TMS frequency will result in the greater MI value.5.LFPs-spike coordinate encoding were analyzed based on spectral coherence.Based on the LFPs-spike dynamic spectral coherence method,the strengths of coordinate encoding of LFPs signals and spike signals in different groups were analyzed.The results showed that high-frequency r TMS can enhance the rate coding of prefrontal cortex neurons and increases LFPs-spike coordinate encoding during working memory,and the higher r TMS frequency result in the greater coherence value.