Pathological Status For The Convulsion Of Electric Stimulation Motor Cortex In Rat In Long-term

Objectives:In many epileptic case we can observe that cerebral cortex of mankind suffer from some kinds of pathology factors for a period and some persons began epilepsia seizure,this sechangecan be evoked a small stimulation.Our prior research indicate convulsant threshold of cortex change from the physical state to the pathologic state in epilepsy patients.The purpose of this research is finding pathological and physiological status for the convulsion of electric stimulation motor cortex in rat in long-term,that is say,the different current intensity stimulate cerebral cortex,the convulsant threshold of cerebral cortex how to change and the pathology of different part cerebral tissue how to change.Methods:In this study determination of the threshold for convulsions is made by direct cortical stimulation in rats.We measured the convulsive threshold at 9:00AM and 3:00PM everyday,while recording electroencephalograms before the stilulation and after the stilulation and subsequently examined histopathological changes.The strong current stimulation(TPS) last 20 weeks and the weak stimulation(TLS) last 8 weeks.Results:(1) At the beginning of the experiment,convulsive thresholds were all above 2000μA although there were significant individual variations in rats of the same group(The strong current stimulation group).But those thresholds quickly declined during the initial 4 weeks of repetitive strong electrical stimulation.The convulsive thresholds approached a constant level after 10 weeks and individual variations is small,it illustrate that pathologic tunnel form nothing at the beginning of the experiment,when the pathologic tunnel or epileptogenic focus forming,the convulsive thresholds will approached a constant level and change nothing.(2) The most common pattern of the electrical activity of rats was waves(100-180uv) which ranged from 5 to 8 Hz,accompanied with a sprinkle of fast waves.The typical single-spike(sharp) firing was observed after rats were stimulated to the TGS's and TPS's.After weeks,the firing index of spike(sharp) waves after reaching TGS's and TPS's significantly increased,that is to say,there was a significant change in the firing index of spike(sharp) waves when stimulation continued for more weeks,it also can be observed in inter-ictal time in rat.(3) In the 6^nd week of the stimulation,chromatin in parts of the nuclei is rarified and arranged unevenly.The longer of the stimulation the more serious the neuron damaged which were showed as a significant decrease in the number of normal pyramidal cells.Majority of pyramidal cells showed as the deformation, karyopycnosis,disaggregating or vanishing of the Nissl's body and acidophilic staining of the endochylema.But there were light damage in the 8 weeks after the weak stimulation,it is the light neuronal degeneration and cellular necrosis.It illustrate that the damage of pyramidal cells in heavy stimulation group were more serious than that of the weak stimulation group.Conclusions:1.The more electric stimulation,the more serious the pyramidal cells damage,epileptogenic focus is easy to form,but the pathologic changs can reversible with the early intervention2.The pathologic changs in hippocampus is serious,the more electric stimulation duration,the more serious the pathologic changs.3.The pathologic convulsant threshold is positive correlation with the stimulus intensity.4.When the pathologic changs is serious,the pathologic convulsant threshold have formed and stabilized...