Analysis of EEG Signals to Extract the Effects of Transcranial Magnetic Stimulation on Depression

Abstract

In the treatment of mental disorders, stimulation of the electrical activity of the brain by Transcranial Magnetic Stimulation has become an increasingly non-invasive treatment method. Mental disorders such as migraine, dementia, bipolar disorder, schizophrenia, stroke, Amyotrophic Lateral Sclerosis, Multiple Sclerosis, Epilepsy, Unconsciousness, tinnitus, depression, anxiety disorders, obsessive-compulsive disorders can be treated by magnetic stimulation of brain. In this study, changes in EEG signals recorded from patients with depression caused by TMS treatment are analyzed using signal processing techniques. The frequency analysis is performed by Fourier transform for each EEG channel of each patient before and after TMS treatment. Here, changes in EEG data of depressed patients with TMS treatment are analyzed using signal processing techniques in MATLAB®. The frequency analyses are obtained from Fourier Transform for each EEG channel of patients before TMS and after TMS treatment. Then these frequency values are compared for each patient. Also the respective IMF (intrinsic mode function) values of each channel are analyzed using the MEMD (Multivariate Empirical Mode Decomposition) algorithm. In this way, the alpha rhythm of EEG datas are detected and the changes in the alpha rhythm of each channel before and after treatment were analyzed.