Effects Of Deep Brain Stimulation On The Neuronal Activities Of The Motor Cortex

Experimental objective:6-hydroxydopamine(6-OHDA) is used to establishmodel rats with Parkinson’s disease(PD), A behavioral examination was tested todetect the motion disorder. To research the change of firing pattern secondary motorcortex (M2)of rats in different condition, and the change of dopamine (DA)neurons ofthe substantia nigra of midbrain.Experimental method: This experiment adopts the stereotaxic technique toinject the6-OHDA in the substantia nigra pars compacta (SNc) and midbrain ventraltegmental areas (VTA) to establish PD rats model, Apomorphine is used to inducerotation to identify whether the PD model is successful or not. Vibrissae-evokedforelimb placing test and postural instability test after PD model were tested.Identification the damage degree of motor function of PD rats was identified so as toexplore more convenient and mild PD model identification method.Numerous studies showed that symptoms of PD were related to the abnormaldischarge of the basal ganglia nuclei. Local field potentials (LFPs) is the sum ofneuronal excitatory and inhibitory activity near the electrode tip and could betterreflect the coordinated variation of the neuronal firing of some region. LFPs wasclosely related to the animal’s motion state. The object of this was the M2-LFPs ofrats. For spectrum analysis and power spectrum density and spectral analysis ofMatlab software were used to explore the rule of the change of M2-LFPs of PD modelrats, normal rats and PD model rats after giving electrical stimulation to hypothalamusventral lateral nucleus so that provides certain theoretical reference for exploring themechanism of deep brain stimulation (DBS).The movement disorders that PD patients suffered from might due to thedeficiency of the dopamine in substantia nigra-striatum pathways, which lead to theabnormal information transition from cortex. Immunohistochemical method wasapplied in this experiment, frozen section and tyrosine hydroxylase tags were used tothe substantia nigra of PD rats to observe damage degree of dopamine neurons in substantia nigra of PD rats. And to explore whether the long time high-frequencyelectrical stimulation can give protective effect to dopamine neurons damage ofsubstantia nigra of PD rats.Experimental conclusion:6-OHDA was used to establish the PD model byinjecting at SNc and VTA. This method was very stable and efficient. To motioninjury degree of the PD rats, vibrissae-evoked forelimb placing test and posturalinstability test could make an accurate evaluation. Electrophysiological experimentsshow that, the LFPs signals at8-12Hz were much more while those at40-100Hzwere much less in experiment group than in control group (P<0.01,P<0.01).The LFPssignals at8-12Hz and12-25Hz were much less (P<0.01,P<0.01) while those at25-40Hz and40-100Hz were much more (P<0.05,P<0.01) after electricalstimulation than before electrical stimulation. Electrical ventrolateral thalamusnucleus stimulation can improve the abnormal discharge from secondary motor cortexin PD rats. TH immunohistochemical experiment of rat nigra neurons found that theTH neurons of PD rats injury side were nearly all apoptosis. After DBS ofhypothalamus ventral lateral nucleus, this status wasn’t obvious improvement.