Empirical Mode Decomposition for Eeg Signal Analysis

Electroencephalogram (EEG) is used to record electrical activity of brain. Human brain is fascinated by the different idea of thoughts and feelings generated from external and internal stimuli. Feature extraction and classification of EEG signal plays an important role in diagnosis of various brain diseases and mental tasks. In this paper, powerful technique of empirical mode decomposition (EMD) for the EEG signal is proposed. For extracting data from nonlinear and nonstationary process EMD is used in wide variety of applications. Intrinsic mode functions (IMFs) resulting from EMD process are considered as set of amplitude modulation (AM) and frequency modulation (FM) signals. Hilbert Huang transform is used for analytic representation of IMF. Features obtained from IMF can be applied to classifier to show effectiveness of EMD process. Keywords— EEG signal analysis, Electroencephalogram (EEG), intrinsic mode function, Hilbert huang transform (HHT) I) INTRODUCTION Brain controls various activities of our body and it is very active part. Brain functions are analyzed by an observing electrical signals generated by neurons. EEG signal measures changes of these signals in terms of voltage fluctuations of brain within very short time period [1]. In modern biomedical applications EEG signal is investigated as function of humancomputer communication. Computers help in recognition of abnormalities in brain from EEG signal. Many neurological disorders can be easily diagnosis with the help of brain rhythms which can be easily recognized by visual inspection of the EEG signal. EEG signal occurs in frequency ranges of delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-13 Hz) and beta greater than 13 Hz. To record electrical signals, electrodes are arranged on the surface of scalp using 10-20 system of an electrode placement. As name indicates that distance between the adjacent electrodes are either 10% or 20% from total front-back or left-right portion of skull. It uses letters and numbers for placement of electrodes. The electrode site is labeled with a letter which corresponds to the area of the brain, and the number which indicates the right hemisphere even, or the left hemisphere – odd. Nasion and Inion are the anatomical landmarks. 10-20 system is shown in given in Fig.1. Fig.1 Electrode placement for 10-20 system INTERNATIONAL JOURNAL OF CURRENT ENGINEERING AND SCIENTIFIC RESEARCH (IJCESR) ISSN (PRINT): 2393-8374, (ONLINE): 2394-0697,VOLUME-2, ISSUE-4,2015 34 Brain Computer Interface (BCI) is an advanced technology that acquires and analyzes signal for achieving communication between brain thoughts, messages and computer [2] [3]. Basic BCI System is shown in Fig.2.