Neuronal Firing Rate And Oscillatory Activity In Subthalamic Nucleus Associated With Parkinson's Disease Progression

Objective To explore whether neuronal firing rate and proportion of oscillatory neuronal activity increase in subthalamic nucleus(STN)is associated with Parkinson's disease(PD)progression.Methods Twenty-two patients with PD treated with STN deep brain stimulation(DBS)at Beijing Institute of Functional Neurosurgery,Xuanwu Hospital,Capital Medical University from March 2015 to March 2016 were analyzed retrospectively.Microelectrode recording was performed in the STN.Single unit analysis including interspike interval(ISI)was used to study neuronal firing rate and patterns.Power spectral analysis was used to evaluate neuronal oscillation.Clinical outcome was assessed using Unified Parkinson's Disease Rating Scales(UPDRS III)pre-and post-surgery.The groups of the early stage and the advanced-stage were defined based on the UPDRS III scores,disease duration and the side of initial symptoms.Results Of total 163 neurons identified from 32 STN,there were 66 neurons with mean firing rate of 46.2±13.6 Hz obtained from the patients in the early-stage group whereas 97 neurons with mean firing rate of 59.9±17.1 Hz were obtained from patients in the advanced-stage group.Power spectral analysis showed that there were 27(40.9%)oscillatory neurons identified from the STN neurons in the early-stage patient group(n=66)whereas 55(56.7%)oscillatory neurons wereidentified from the STN neurons in the advanced-stage patient group(n=95).Further analysis found that 29.7%(8/27)? oscillatory neurons were observed in the early stage group whereas 52.7%(29/55)? oscillatory neurons were observed in the advanced stage group.When comparing the mean firing rate and proportion of oscillatory neurons in the STN of early-stage group with that of neurons in the STN of advanced-stage group,it was found that there was a 29.6% increase STN mean firing rate of neurons(46.2±13.6 Hz vs.59.9±17.1 Hz,P<0.05)and a 36.8% increase proportion of oscillatory neurons(40.9% vs.56.7%)between the two groups.In particular,a 77.8% increase proportion of ? oscillatory neurons was obtained between the early-stage and advanced-stage groups(29.7% vs.52.8%,P<0.01)Conclusion 1.A large number of oscillatory neurons,e.g.tremor oscillatory neurons and ? oscillatory neuronshas been found in the STNof two PD patient groups supporting the view of dysfuntion of basal ganglia involved in pathophysiology of Parkinson's disease.2.The data provide the evidence that the firing rate and proportion of subthalmic oscillatory neurons increase is associated with the advanced stage PD patient group in comparison with the early stage PD patient group.3.The results strongly suggest that both subthalamic neuronal firing rate and proportion of oscillatory neurons,especially ? oscillatory neurons increase with PD progression.