ObjectiveThe optimal target of deep brain stimulation (DBS) for treating intractable epilepsy is still undefined. Cumulative studies suggest that the mediodorsal thalamic nucleus (MD) is involved in seizure activity, the purpose of this study was to investigate the effect of high frequency stimulation in MD on pentylenetetrazole (PTZ)-induced seizures in rats. MethodsThe experimental rats (Male Sprague-Dawley rats 280-350 g) were all provided by Experimental Animal Center, Zhejiang Academy of Medical Science, Hangzhou, China. The rats were given unilateral or bilateral stimulation of the MD at 100 Hz (HFS group) and sham stimulation, others were given unilateral stimulation of the MD at 1 Hz (LFS group). EEGs in the cortex and seizure behavior were recorded with the Neuroscan system at the same time. ResultsNeither LFS nor HFS of the MD changed the latency to the first spikes or EEG manifestations for stage 3 and stage 5 seizures; animals receiving unilateral or bilateral HFS of the MD decreased the number of stage 5 EEG seizure synchronized with the convulsive episodes; LFS and sham stimulation showed multiple periods of continuous spikes which accompanied stage 5 or stage 4 seizures. HFS of unilateral or bilateral MD, but not LFS, decreased the seizure stage, the number of clonic movement episodes, and the duration of acute PTZ-induced seizures. The average latency to onset of myoclonic jerks did not differ among groups. Unilateral and bilateral HFS of the MD had a similar antiepileptic effect. ConclusionHFS of the MD may be of value as a new antiepileptic approach for patients with generalized epilepsy, besides, the seizure model, should be fully considered in clinical application.
The dysfunction of subthalamic nucleus is the main cause of Parkinson’s disease. Local field potentials in human subthalamic nucleus contain rich physiological information. The present study aimed to quantify the oscillatory and dynamic characteristics of local field potentials of subthalamic nucleus, and their modulation by the medication therapy for Parkinson’s disease. The subthalamic nucleus local field potentials were recorded from patients with Parkinson’s disease at the states of on and off medication. The oscillatory features were characterised with the power spectral analysis. Furthermore, the dynamic features were characterised with time-frequency analysis and the coefficient of variation measure of the time-variant power at each frequency. There was a dominant peak at low beta band with medication off. The medication significantly suppressed the low beta component and increased the theta component. The amplitude fluctuation of neural oscillations was measured by the coefficient of variation. The coefficient of variation in 4-7 Hz and 60-66 Hz was increased by medication. These effects proved that medication had significant modulation to subthalamic nucleus neural oscillatory synchronization and dynamic features. The subthalamic nucleus neural activities tend towards stable state under medication. The findings would provide quantitative biomarkers for studying the mechanisms of Parkinson’s disease and clinical treatments of medication or deep brain stimulation.
The effect of deep brain stimulation (DBS) surgery treatment for Parkinson's disease is determined by the accuracy of the electrodes placement and localization. The subthalamic nuclei (STN) as the implant target is small and has no clear boundary on the images. In addition, the intra-operative magnetic resonance images (MRI) have such a low resolution that the artifacts of the electrodes impact the observation. The three-dimensional (3D) visualization of STN and other nuclei nearby is able to provide the surgeons with direct and accurate localizing information. In this study, pre- and intra-operative MRIs of the Parkinson's disease patients were used to realize the 3D visualization. After making a co-registration between the high-resolution pre-operative MRIs and the low-resolution intra-operative MRIs, we normalized the MRIs into a standard atlas space. We used a special threshold mask to search the lead trajectories in each axial slice. After checking the location of the electrode contacts with the coronal MRIs of the patients, we reconstructed the whole lead trajectories. Then the STN and other nuclei nearby in the standard atlas space were visualized with the grey images of the standard atlas, accomplishing the lead reconstruction and nerve nuclei visualization near STN of all patients. This study provides intuitive and quantitative information to identify the accuracy of the DBS electrode implantation, which could help decide the post-operative programming setting.