부산대학교 도서관

The hypotheses that orthostatic tremor is generated by a central oscillator is been tested in this paper. In order to understand the mechanisms of the central network its sources need to be found. The cortical sources of both the basic and first “harmonic” frequency of orthostatic tremor are addressed in this paper. The Dynamic Imaging of Coherent Sources (DICS) was used to find the coherent sources in the brain. The three essential constraints for detecting deep sources in the brain using EEG data were tested by three model simulations. The optimal number of electrodes, length of the data and the signal to noise ratio required for error-free localization was tested. In all the orthostatic tremor patients the corticomuscular coherence was also present in the basic and the first harmonic frequency of the tremor. The basic frequency constituted a network of primary leg area, supplementary motor area, primary motor cortex, two pre-motor sources, diencephalon and cerebellum. The first harmonic frequency was in the region of primary leg area, supplementary motor area, primary motor cortex, diencephalon and cerebellum. Thus the generation of these two oscillations involves the same network structure and indicates the oscillation at double the tremor frequency is a harmonic of the basic tremor frequency. The orthostatic tremor could have the central oscillator in the brain.