Effect of Deep Brain Stimulationon Neural Activity of Subthalamic Nucleus in Rats

To date, deep brain stimulation (DBS) is the most effective clinical treatment for Parkinson's disease (PD). However the mechanism of action of DBS is still under investigation which hampers the further improvement of DBS and study of the pathogenesis of PD. In past decade, kinds of experiment apparatuses and means were applied to explore the mechanism of action of high frequency stimulation (HFS) on target nucleus, such as subthalamic nucleus (STN). Among these, the change of neural spiking activity of STN during ongoing HFS can reflect precisely the influence of HFS on nucleus, thus, is the better method to determine the mechanism. However, large stimulus artifacts (SA) have greatly restrained the application of this technique. An online filter method based on template subtraction was developed and evaluated for the removal of stimulus artifacts and their harmonics from extracellular neural recording. The data presented here illustrated that although this algorithm is simple and low computation intensive, it can well recover spikes for low SNR signal, even spikes completely submerged by SA. Utilizing this effective algorithm, the relation between the type of neural response and the frequency and amplitude of stimulation was determined; meanwhile effect of HFS with clinically effective parameters on mean firing rats was studied and analyzed. Experiment results illustrated that the percentage of STN neurons which showed inhibition to HFS rise with the increment of frequency and amplitude of stimulus. In addition, Experiment results showed that the change of mean firing rat may not be directly involved with the symptoms of Parkinson's disease (PD), and the increase of burst neural activity should more likely be the neurophysiologic basis of PD. Furthermore, it was found that inhibition of spontaneous neural activity leading to reduction of mean firing rate and burst activity may be the part of mechanism of action of deep brain stimulation.