Abstract
Background: To decipher EEG (Electroencephalography), intending to locate inter-ictal and ictal discharges for supporting the diagnoses of epilepsy and locating the seizure focus, is a critical task. The aim of this work was to find how the ensemble model distinguishes between two different sets of problems which are group 1: inter-ictal and ictal, group 2: controlled and inter-ictal using approximate entropy as a parameter.
Methods: This work addresses the classification problem for two groups; Group 1: “inter-ictal vs. ictal” for which case 1(C-E), and case 2(D-E) are included and Group 2; “activity from controlled vs. inter-ictal activity” considering four cases which are case 3 (A-C), case 4(B-C), case 5 (A-D) and case 6(B-D) respectively. To divide the EEG into sub-bands, DWT (Discrete Wavelet Transform) was used and approximate Entropy was extracted out of all the five sub-bands of EEG for each case. Bagged SVM was used to classify the different groups considered.
Results: The highest accuracy for Group 1 using Bagged SVM Ensemble model for case 1 was observed to be 96.83% with testing data; which was similar to 97% achieved by using training data. For case 2 (D-E) 93.92% accuracy with training and 84.83% with testing data were obtained. For Group 2, there was a large disparity between SVM and Bagged Ensemble model, where 76%, 81.66%, 72.835% and 71.16% for case 3, case 4, case 5 and case 6 were obtained. While for training data set, 92.87%, 91.74%, 92% and 92.64% accuracy was attained, respectively. The results obtained by SVM for Group 2 showed a huge difference from the highest accuracy achieved by bagged SVM for both the training and the test data.
Conclusion: Bagged Ensemble model outperformed SVM model for every case with a huge difference with both training as well as test dataset for Group 2 and marginally better for Group 1.
Keywords: EEG classification, approximate entropy, discrete wavelet transform, bagged SVM, ensemble model, epileptic states.
Graphical Abstract
[http://dx.doi.org/10.1111/j.0013-9580.2005.66104.x] [PMID: 15816939]
[http://dx.doi.org/10.4103/0972-2327.160093] [PMID: 26425001]
[http://dx.doi.org/10.4103/0972-2327.128643] [PMID: 24791085]
[http://dx.doi.org/10.1016/j.eplepsyres.2004.05.004] [PMID: 15279865]
[http://dx.doi.org/10.1016/j.sigpro.2008.01.026]
[http://dx.doi.org/10.1016/j.eswa.2007.12.065]
[http://dx.doi.org/10.1016/j.jneumeth.2010.08.030] [PMID: 20817036]
[http://dx.doi.org/10.1007/s11760-012-0362-9]
[http://dx.doi.org/10.1016/j.neucom.2013.11.009]
[http://dx.doi.org/10.1073/pnas.88.6.2297] [PMID: 11607165]
[http://dx.doi.org/10.1109/IJCNN.2003.1223688]
[http://dx.doi.org/10.4103/0301-4738.37595] [PMID: 18158403]
[http://dx.doi.org/10.1142/S0129065712500025] [PMID: 23627588]
[http://dx.doi.org/10.1016/j.eswa.2012.02.040]
[http://dx.doi.org/10.1016/j.bspc.2011.07.007]
[http://dx.doi.org/10.1109/TBME.2013.2254486] [PMID: 23629837]
[http://dx.doi.org/10.1016/j.jneumeth.2015.01.015] [PMID: 25614384]
[http://dx.doi.org/10.1049/iet-cds.2017.0216]
[http://dx.doi.org/10.1007/s11517-015-1351-2] [PMID: 26296799]
[http://dx.doi.org/10.4236/jbise.2010.36078]
[http://dx.doi.org/10.1007/s12553-018-0265-z]
[http://dx.doi.org/10.1016/j.cmpb.2010.11.014] [PMID: 21168234]
[http://dx.doi.org/10.1177/155005940503600106] [PMID: 15683194]
[http://dx.doi.org/10.1016/j.cmpb.2005.06.012] [PMID: 16219385]
[http://dx.doi.org/10.1016/j.eswa.2007.11.017]
[http://dx.doi.org/10.1016/j.cmpb.2010.11.014] [PMID: 21168234]
[http://dx.doi.org/10.1016/j.eswa.2011.07.008]
[http://dx.doi.org/10.1016/j.jneumeth.2015.01.015] [PMID: 25614384]
[http://dx.doi.org/10.1016/j.patrec.2017.03.023]
[http://dx.doi.org/10.1080/03091902.2017.1394389]