| Electroencephalo-signals (EES), which are recorded through the electrodes, are the spontaneous, rhythmical electrical activities in the cortex or on the surface of scale. It contains a large number of physiological and pathological information, which can help doctors to improve the reliability and accuracy in the diagnosis of brain-neural system disease, so it plays a key role in the clinical diagnosis. The EES analysis and extraction at home and abroad on the research field are growing. Moreover, with the development of signal processing technology, many classic and modern signal processing methods have been applied to analyze EES, It can be said that former work has been provided a very good foundation.The innovative viewpoints in the work are represented in the following two aspects:1. A new method, called as Fourier multi-resolution analysis (FDMRA), was proposed based on the Fourier transform and applied to resolve EES into basic rhythms ofδwave,θwave,αwave andβwave to research the dynamic characteristics of all rhythms of EES. Then we calculated and compared four components power values of ten samples in different conditions.(1) The results of four main components (δ,θ,α,β) powers of EES in the opened eyelids states and closed eyelids states:In the closed eyelids states,αcomponent powers of dual channels are 7.31±5.92μV~2 and 8.72±6.07μV~2, p>0.05.βcomponent powers of dual channels are 1.2±0.67μV~2and 1.12±0.57μV~2,p>0.05.δcomponent powers of dual channels are 17.29±13.11μV~2 and 17.32±12.87μV~2, p>0.05.θcomponent powers of dual channels are 3.38±2.95μV~2 and 3.35±2.86μV~2, p>0.05.There are no significantly different between the power values of each component ofα,β,δandθin the symmetric dual channels.In the opened eyelids states,αcomponent powers of dual channels are 1.58±0.95μV~2 and 1.53±0.94μV~2, p>0.05.βcomponent powers of dual channels are 2.39±1.56μV~2and 2.31±1.89μV~2, p>0.05.δcomponent powers of dual channels are 15.86±7.57μV~2 and 14.64±7.28μV~2, p>0.05.θcomponent powers of dual channels are 3.38±2.95μV~2 and 3.35±2.86μV~2, p>0.05. There are no significantly different between the power values of each component ofα,β,δandθin the symmetric dual channels. Compared the opened eyelids states and the closed eyelids states, the changes of four components of dual channels EES are that the power percentages ofαcomponents are decreases of 13.45% and 17.34%, respectively, in the opened eyelids states than the closed eyelids states, p<0.05. The power percentages ofβcomponents are increases of 11.21% and 12.21%, respectively, in the opened eyelids states than the closed eyelids states, p<0.05. There are significantly different between the power values ofαandβcomponents in the opened eyelids states and in the closed eyelids states. The power percentages ofδcomponents are increases of 7.43% and 8.8%, respectively, p>0.05, the power percentages ofθcomponents are decreases of 2.57% and 3.79%, respectively, p>0.05. There are no significantly different between the power values ofθandδcomponents in the opened eyelids states and in the closed eyelids states.The above results suggested thatα,βcomponents are closely related to the brain function state.(2) The results of four main components (δ,θ,αandβ) of EES in the relaxed states and flash stimulation states.In the relaxed states, the power percentages ofαcomponents are 12.17±0.7(%) and 13.1±0.66(%), p>0.05. The power percentages ofβcomponents are 4.4±0.9(%) and 5.07±0.37(%), p>0.05. The power percentages ofδcomponents are 56.74±1.49(%) and 53.9±1.47(%), p>0.05. The power percentages ofθcomponents are 20.89±0.71(%) and 21.6±0.72(%),p>0.05.There are no significantly different between the power percentage values of each component ofα,β,δandθcomponents in the symmetric dual channels. In the flash stimulation states, the power percentages ofαcomponents are 15.26±0.69(%) and 15.14±0.64(%), p>0.05. The power percentages ofβcomponents are 7.54±0.39 (%) and 8.96±0.51(%), p>0.05. The power percentages ofδcomponents are 43.73±1.1(%) and 41.27±0.97(%), p>0.05. The power percentages ofθcomponents are 24.2±0.75(%) and 24.1±0.75(%), p>0.05. There are no significantly different between the power percentage values of each component ofα,β,δandθcomponents in the symmetric dual channels.Compared the relaxed states and the flash stimulation states, the changes of every component as follows: The power percentages ofθcomponents are increases of 3.3% and 2.5%, respectively, p>0.05, there is no significantly different. The power percentages ofαcomponents are increases of 2.54% and 2.04%, respectively, p<0.05.The power percentages ofβcomponents are increases of 3.09% and 3.88%, respectively, p<0.05. There are significantly different between the power percentage values ofαcomponent andβcomponent in the relaxed states and in the flash stimulation states.The above results suggested thatα,βcomponents are increased markedly and implied that these two waves are related to stimuli-response. From above, we can get that FDMRA has clear physical meaning and it has a mature theory. The method was that use of FDMRA can perfectly extract the time domain and the frequency domain information, as well as the smooth and the fine information in different levels. So, it can get the more information than wavelet multi-resolution analysis.2. We presented the type of new magnitude-squared coherence functions (MSCFs) and proved OMSCF (old magnitude-squared coherence function) identities to one, so that the OMSCF couldn't be used to extract any coherence information between signals. And we demonstrated the new Magnitude-squared coherence function, which can exactly extract the coherence between two signals by each component and mathematically proved the conditions that they are equal to 1 or 0.By Calculated and compared the coherences of ten samples in the relaxed states and flash stimulation states, we found that four main characteristic waves coherences are increased and suggested that flash stimulation can enhance the coherence of EES.It is found that the coherence spectral lines of the same-type of MSCF (SMSCF) are generally higher than the different-type of MSCF (DMSCF). It shows that the coherence of same-type components in the same frequency is better in the symmetric area, and it has stronger inphase.From the results we have obtained, it can be inferred that the methods using the EES analysis system, which are described in the paper, to process EES, are feasible and effective. |
PDF Full Text Request