The Research Of Electrical Signals Of Parafascicular Nucleus Of Thalamus In Rat Of Parkinson’s Disease

Objective: Parkinson’s Disease（PD）is a kind of common degenerative disease of nervoussystem, which is characterized by several clinical motility disorders such as rest tremor, etc andis caused by the collapse of dopaminergic neurons of substantia nigra..Parafascicular nucleus ofthalamus（PF） has projections to multiple nuclei in the basal ganglia, Through the collectionand analysis of the discharge change of PF after lesion and the discharge characteristics of PFduring specific behavior, this research can provide effective theoretical support for the basicresearch about clinical treatment of PD.Method: In this study, the PD model was set up by directly injecting6-OHDA intomidbrain ventral Tegmental Area（VTA） and Substantia Nigra Compacta（SNc），with the dosewas2and3μL respectively. Spike and the Local Field Potential（LFP）of PF of the silentnormal and PD rats was collected through the implanted multichannel electrode array in PF andrecorded with the signal acquisition instrument produced by American Plexon company. Wetrained the rats to grab food, collected and recorded spike and Local Field Potential when ratswere grabbing food. Finally, through blue dot experiment, the accuracy of the position wasexamined, and the damage of substantia nigra was observed by immunohistochemistrytechnology.Result: Offline Sorter classified the high frequency spike signals collected. PF neuronscould be divided into two categories including the type of neuron A（type A） and the type ofneuron B（type B） on the basis of waveform, time-histories, discharge mode and PrincipalComponent Analysis（PCA）, etc. The wave of type A was taller, and the time-histories waslonger than type B. The wave of the type B was placid, and the discharge patterns was moreregular than the type A. After the original signal classification by the Offline Sorter, weimported them to NeuroExplorer to analyse the rate of spike, the ISI coefficient of variation,etc. Compared with the normal rats, the discharge rate of the two kinds of neuron of PD ratsboth had no significant difference when the rats were in a lucid under stationary state. But thedischarge pattern of the type A became more regular, and the discharge pattern of the type Bbecame irregular after molding. By importing the LFPs data into Matlab to analyze, it wasfound that the percentage of0.7~20Hz frequency signal of the PD rats’ PF was much lowerthan the normal rats. And the percentage of20~40Hz frequency signal of the PD rats’ PF waslittle higher than the normal rats. The time-frequency diagram could reflect energy distributionintuitively. The low frequency energy of normal group rats was higher than the experimentalgroup rats with gorgeous color, but at20~40Hz frequency the color of the experimental grouprats was few more gorgeous than normal group rats. The results were consistent with the resultsof spectrum analysis.By studying the discharge changes when rats was preying, we found that preparationperiod in the prey action of PD rats is significantly longer than the normal rats. AsNeuroExplorer showed, the discharge rate of two kinds of neurons was significantly reduced.The ISI coefficient of variation of the type B increased significantly, but the type A only had anincreasing trend and there was no significant difference. Compared with the normal rats, theproportion of the range of0.7~20Hz in the total signal of the PD rats was much lower.However, the range of the20~40Hz had no significant difference and40~100Hz was higherthan the normal group rats. The time-frequency analysis showed that the area with gorgeouscolor of low frequency signal of the nomal group rats was wider than the experimental grouprats, and the results were consistent with the results of spectrum analysis.Conclusion: Through a variety of classification algorithm analysis, PF neurons weredivided into two categories. when the rats was in a lucid under stationary state,the dischargerate of PF neurons had not changed significantly, but discharge patterns had a significantdifference. Through the spectrum analysis of LFPs, the proportion of the range of0.7~20Hz intotal signal decreased significantly, as the range of the20~40Hz had a significantly higherpercentage. The electric property of PF was changed because the6-OHDA damaged thesubstantia nigra dopaminergic neurons. This suggested that the PF was associated with PD.Under the prey behavior,,the discharge rate of PF neurons reduced significantly, and dischargepatterns had no difference and the proportion of the range of40~100Hz frequency signal increased significantly. Under the specific behavior，PF spike and LFPs in PD rats werechanged，which suggested that there was a link between PF and thalamus-cortex loop. From thepoint of view of electrophysiology, this research provide a theoretical basis for PF becoming anew PD treatment point.