ABSTRACT
Event-related desynchronization (ERD) is the basic feature of electroencephalogram (EEG), and the brain-computer interface based on motor imagery (MI-BCI) with the foundation of the analysis of ERD is of great significance in motor function recovery. The valid ERD characteristics extracted from EEG are the key to the performance of the BCI, so the study of which kind of stimulation mode can prompt subjects to generate more obvious characteristics of ERD is crucial. Four different stimulation modes are designed in this paper, and the effects of motion imagery tasks under static text stimulation, grip video stimulation, serial motion video stimulation of fingers as well as serial motion video stimulation of fingers with sound on the characteristics of ERD are analyzed. Combining the analysis of time-frequency spectrum, the power spectral density curve, ERD value and brain topographic map, it is shown that the ERD under serial motion video stimulation of fingers and serial motion video stimulation of fingers with sound modes is much stronger and has wider range of activation, and the BCI based on the analysis of ERD will have a better effect on practical application. As a result, the recognition and acceptance of the users of BCI system are improved in some extent.
ABSTRACT
The event-related desynchronization/synchronization(ERD/ERS) time courses of lower and upper alpha band rhythms during hand motor imagery are investigated respectively by Fourier Sectral Entropy (FSE) in this paper. By analyzing one group of BCI competition data, it was found that FSE within upper alpha band displays a pronounced increase and decrease over contralateral and ipsilateral brain areas respectively at the onset of hand motor imagery, which is corresponding to the antagonistic ERD/ ERS patterns in previous studies. Different from the upper alpha activity pattern, FSE within lower alpha band displays a consistent increase over both two hemispheres hand representative areas. The preliminary results show that FSE could disclose the different behaviors of the upper and lower alpha band rhythms so that a new idea with the complexity measure is provided to characterize functional dissociation of lower and upper frequency alpha rhythms in relation to hand motor imagery.
ABSTRACT
The event-related desynchronization/synchronization(ERD/ERS) time courses of lower and upper alpha band rhythms during hand motor imagery are investigated respectively by Fourier Sectral Entropy (FSE) in this paper. By analyzing one group of BCI competition data, it was found that FSE within upper alpha band displays a pronounced increase and decrease over contralateral and ipsilaterai brain areas respectively at the onset of hand motor imagery, which is corresponding to the antagonistic ERD/ERS patterns in previous studies. Different from the upper alpha activity pattern, FSE within lower alpha band displays a consistent increase over both two hemispheres hand representative areas. The preliminary results show that FSE could disclose the different behaviors of the upper and lower alpha band rhythms so that a new idea with the complexity measure is provided to characterize functional dissociation of lower and upper frequency alpha rhythms in relation to hand motor imagery.
ABSTRACT
To evaluate the prognostic significance of ERD5 in gastric cancer, the frequency of their expression was examined by the immunohistochemical method in 70 cases of gastric cancer with alcohol-fixed, paraffin embedded specimens which were obtained surgically at the department of Surgery, Gyeongsang National University Hospital from October, 1990 to May, 1993. Correlations between ERD5 positivity and clinicopathological parameters were analysed with Student's t-test and Chi-square test, and the survival rate according to whether the ERD5 was present or not was evaluated with Kaplan-Meier analysis model. Of the 70 patients, 40 cases showed a positive rate for estrogen receptor and 27 cases(67.5%) were male and 15 cases(50%) were female. There was no significant difference between the ERD5 positive rate and sex distribution. In age distribution, the ERD5 positive rate was most high(67%) in the 5th decade, but it was not significant statistically. There was no significant difference between the ERD5 positive rate and the WHO pathologic classification. In Lauren's classification, the intestinal type of gastric cancer had a higher positive rate(69%) than diffuse type(50%). In Ming's classification, the expanding type(82%) of gastric cancer had a higher positive rate than the infiltrative type(50%). A statistically significant difference was found between the expanding type and infiltrative type(P<0.05). There were no significant differences between the ERD5 positive rate and the TNM staging or the degree of differentiation of cancer cells. There was no significant difference between the ERD5 positive rate and the serum CEA level. Of the 70 patients, the overall 5-years survival rate was 37 % and 5-years survival rate of positive ERD5 cases had a higher rate (38.4%) than negative cases (35.1%) but there was no statistically significant difference. In conclusion, the ERD5 positive rate was significantly high in the patient with expanding type of gastric cancer in Ming's classification and intestinal type of gastric cancer in Lauren's classification. But, there was no significant difference in the survival rates between the ERD5 positive group and the ERD5 negative group.