南京大学学报(自然科学版) ›› 2022, Vol. 58 ›› Issue (2): 264–274.doi: 10.13232/j.cnki.jnju.2022.02.010

• • 上一篇    

基于欧式空间⁃加权逻辑回归迁移学习的运动想象EEG信号解码

陈黎1,2, 龚安民3, 丁鹏1,2, 伏云发1,2()   

  1. 1.昆明理工大学信息工程与自动化学院,昆明,650500
    2.昆明理工大学脑认知与脑机智能融合创新团队,昆明,650500
    3.武警工程大学信息工程学院,西安,710000
  • 收稿日期:2021-09-13 出版日期:2022-03-30 发布日期:2022-04-02
  • 通讯作者: 伏云发 E-mail:fyf@ynu.edu.cn
  • 作者简介:E⁃mail:fyf@ynu.edu.cn
  • 基金资助:
    国家自然科学基金(81470084)

EEG signal decoding of motor imagination based on euclidean space⁃weighted logistic regression transfer learning

Li Chen1,2, Anmin Gong3, Peng Ding1,2, Yunfa Fu1,2()   

  1. 1.School of Information Engineering and Automation,Kunming University of Science and Technology,Kunming,650500,China
    2.Brain Cognition and Brain?Computer Intelligence Integration Group,Kunming University of Science and Technology,Kunming,650500,China
    3.College of Information Engineering,Engineering University of PAP,Xi'an,710000,China
  • Received:2021-09-13 Online:2022-03-30 Published:2022-04-02
  • Contact: Yunfa Fu E-mail:fyf@ynu.edu.cn

摘要:

基于脑电图(Electroencephalography,EEG)信号的运动想象(Motor Imagery,MI)意图识别是脑机接口(Brain?Computer Interface,BCI)研究中的重要问题.然而,EEG信号存在严重的个体性差异,不同被试之间的EEG信号特征空间分布差异很大,不同被试之间的分类模型不能通用.针对这一问题,提出一种基于欧式空间的加权逻辑回归迁移学习方法,算法首先将不同被试的EEG数据进行欧几里得空间对齐,使各信号更加相似,减少差异性,然后计算特定被试共空间模式(Common Spatial Pattern,CSP)获得不同的特征值,并计算这些特征值的KL(Kullback?Leibler)散度,进而利用KL散度调整迁移学习的加权逻辑回归算法,得到分类模型.实验结果表明:对于BCI竞赛IV中的数据集2a,提出的方法可以极大地提升BCI的学习性能,算法分类准确率比基线算法(线性判别分析)高出15%.在数据样本增多的情况下,被试的分类准确性也得到了明显的提升,和同类算法相比,分类准确率提升4%,说明提出的算法能进一步提高BCI的学习性能,改善分类模型的通用性问题.

关键词: 运动想象, 脑机接口, 欧式对齐, 迁移学习, 逻辑回归

Abstract:

Motor imagery (MI) intention recognition based on electroencephalography (EEG) signals is an important issue in brain?computer interface (BCI) research. However,EEG signals have serious individual differences,while the spatial distribution of EEG signal characteristics between different subjects is very different,and the classification model between different subjects cannot be universal. To solve this problem,this paper proposes a weighted logistic regression transfer learning method based on Euclidean space.The algorithm first aligns the EEG data of different subjects in Euclidean space to make the signals more similar and reduce the difference,and calculate the different feature values?obtained by the common spatial pattern (CSP) of a specific subject. Then,it calculates the KL (Kullback?Leibler) divergence of these eigenvalues,using the KL divergence to adjust the weighted logistic regression algorithm of transfer learning to obtain the classification model.The experimental results show that, for the data set 2a in the BCI competition IV,the proposed method greatly improves the learning performance of BCI,and the classification accuracy is 15% higher than that of the baseline algorithm (Linear Discriminant Analysis).In case of an increase in data samples,the classification accuracy of the subjects has been significantly improved. Compared with similar algorithms,the classification accuracy of the proposed algorithm increases by 4%,indicating that the algorithm in this paper furtherly improves the BCI learning performance and the generality of the classification model.

Key words: motor imagery, brain?computer interface, Euclidean alignment, transfer learning, logistic regression

中图分类号: 

  • TP391.41

图1

BCI竞赛IV数据集2a:(a)单次MI任务时序图;(b)22个EEG电极位置图,分别为Fz,FC3,FC1,FCz,FC2,FC4,C5,C3,C1,Cz,C2,C4,C6,CP3,CP1,CPz,CP2,CP4,P1,Pz,P2,POz,左侧乳突参考,右侧乳突接地;(c) 3个EOG头皮电极位置图"

图2

本文提出方法的模型"

图3

CSP特征提取方法示意图"

图4

被试的t?SNE可视化:(a)被试1的左右手EA对齐算法对齐示意图,每行是不同的导联上的EEG信号;(b)九个被试的t?SNE可视化;(c)被试1作为目标被试的t?SNE可视化"

表1

对九个被试使用四种方法进行分类的分类准确度比较"

被试方法1方法2方法3方法4
LDASVMLDASVMLDASVMLDASVM
Avg0.620.690.620.680.630.630.700.69
A010.670.810.640.810.740.710.830.81
A020.520.540.530.540.490.490.500.51
A030.820.900.820.900.780.800.940.93
A040.550.560.540.570.560.550.600.59
A050.500.500.500.500.490.490.490.49
A060.530.550.520.550.550.540.600.59
A070.570.610.570.590.560.560.610.60
A080.820.940.790.930.900.890.940.93
A090.680.800.680.780.660.680.820.81

表2

本文方法和其他研究者提出的方法在BCI竞赛Ⅳ数据集2a上的分类准确度对比"

被试A01A02A03A04A05A06A07A08A09Avg
本文方法0.860.630.960.680.530.680.760.960.840.77
Lotte and Guan[28]0.700.510.930.570.660.560.730.870.810.70
He and Wu[22]0.720.560.840.650.600.670.610.860.820.70
Fiebig et al[29]0.880.600.830.520.500.570.770.920.730.70
LDA0.680.510.810.540.490.540.550.830.680.62
SVM0.790.540.910.560.500.560.610.940.790.68
Azab et al[30]0.830.570.870.580.670.600.750.980.750.73

图5

被试10~100个样本使用六种方法评估的分类准确度"

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