| Parkinson’s disease(PD) is a common nervous system degenerative disease. The development of PD motor symptoms such as tremor, rigidity and bradykinesia is closely related to the lack of dopamine in substantia nigra and striatum. Taking dopaminergic agents to replenish the missing dopamine can effectively suppress the symptoms. Therefore, drug therapy becomes the foundation of clinical treatment to Parkinson’s disease. Many studies have showed that the neuron paradoxical discharge in basal ganglion, thalamus and cortex circuit is associated with PD. The local field potentials of subthalamic nucleus(STN) with high temporal and spatial resolutions can provide wealthy information of neural oscillation, and also reflect the brain functional states to some extent. As a kind of stimulation, medication may affect the brain functional states. Furthermore, the influence of medication is relevant to PD’s therapeutic mechanism.This paper analysed the effect of medication on the neural activity in STN base on the local oscillatory network with multi-modal behaviors including rhythm, balancing and coupling behaviors, in order to investigate the relationship between local oscillatory network change and PD motor symptoms with medication. This study aimed to provide quantitative biomarkers for the clinical treatments by medication or deep brain stimulation, and build a bridge between neural activity and PD symptoms.The subthalamic nucleus local field potentials were recorded from 9 patients with Parkinson’s disease undergoing bilateral deep brain stimulator implantation at the states of on and off medication. Resting state signals were monitored byelectromyography to make sure there was 25 s data without tremor available for analysis. Unified Parkinson’s disease rating scale(UPDRS) score was collected three months before the surgery. The rhythm behaviors including synchronization and dynamic-variable features were analyzed using power spectrum analysis in terms of coefficient of variation(CV) of time-varying power. The balancing behaviors were analyzed using power ratio of cross-frequency. The coupling behaviors were analyzed by using the cross-frequency power coupling. This paper can be divided into two parts. Firstly, features significantly influenced by medication were extracted by statistical analysis. Secondly, the relationship between the features and PD motor symptoms were investigated.Results of power spectrum analysis demonstrated that low beta band showed desynchronization, and theta band synchronization was increased after taking medication. While both beta and theta band synchronization are related with rigidity and bradykinesia,the results of CV of time-varying power indicated temporal stability of theta and high gamma band synchronization after taking medication. In addition, they are relevant to overall motor symptoms of PD. After taking medication the balance behavior between 4~10Hz and 10~20Hz was decreased, which was related with the rigidity and bradykinesia. On the other hand, balance between 12~20Hz and 20~38Hz was increased, which was related with tremor symptom. Furthermore, the coupling behavior of 30~38Hz and 4~10Hz, 49~55Hz and 25~30Hz, 50~60Hz and 4~10Hz, 59~65Hz and 20~28Hz was affected by medication. However, just coupling behavior of 59~65Hz and 20~28Hz was related to PD symptoms of bradykinesia.Medication affects multiple features of the local oscillatory network of STN. Some of those are closely related with PD motor symptoms. The findings would provide quantitative biomarkers for studying the mechanisms and treatments by medication or deep brain stimulation of Parkinson’s disease. |
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