Research On Artifact Real-time Removal Method Of EEG Signal In EEG-fMRI Hybrid Brain-computer Interface

With the development of brain science,people are becoming more and more interested in the mechanism of the brain.With the progress of science and technology,more and more technologies have been applied to the field of brain research.EEG and functional magnetic resonance imaging(fMRI)are the two most widely used methods at present.The two methods have their respective advantages of spatial and temporal resolution.The combination of these two methods become a new trend of research.But in the MRI scanning environment,the acquisition of EEG signals will introduce strong artifacts.The main work of this paper is to build a brain machine interface system in the magnetic resonance environment and remove the MRI artifacts introduced in the EEG.First of all,the reasons for the occurrence of magnetic field artifacts are introduced,and the categories and characteristics of artifacts are analyzed in detail.Then it introduces the denoising methods proposed by predecessors,among which the most commonly used algorithms are the average artifact subtraction algorithm(AAS)and the PCA based optimal basis sets,denoising algorithm(OBS).AAS algorithm is relatively simple,and does not require high computation,but it only applies to idealized noise models,with larger residual artifacts in the output signal.Although the OBS algorithm greatly reduces the residual artifacts,it still has some residual noise,and it is easy to remove the components of the EEG signal in the denoising process and destroy the integrity of the EEG signal.In this paper,a new denoising algorithm is proposed for the residual artifacts,that is,in the process of constructing the optimal basis sets,the correlation coefficients between the eigenvectors and the noise template are considered,and the new optimal basis sets will be constructed to denoise.Then a minimum mean square adaptive filter is proposed to remove the residual artifacts in the signal and preserve the integrity of EEG.Then,the author uses the Brain Amp MR equipment of Brain Product to build the brain machine interface experiment system in the MRI scanning environment,and implemente the denoising algorithm in the system,and combined with the brain machine interface experiment system to carry on the online experiment.This paper mainly uses the P300 character input experiment system as the brain machine interface experiment under the MRI scanning environment.Through the P300 character input experiment,the effect of the algorithm is verified,and the experimental results are compared with the other traditional denoising algorithm.