EEG based Visualization and Analysis of Emotional processing in Major Depressive Disorder

Major Depressive Disorder is one of the principal causes of disability globally. It is characterized by low self-regard and thoughts of hopelessness. This study aims at analyzing the brain activity during emotional processing in depressed patients. Fifteen adults with a HDRS-17 score of greater than 20 participated in the study. EEG was recorded while viewing two categories of IAPS pictures namely, neutral and high valence high arousal. SAM scale was utilized to find the perceptual emotions of the participants. The behavioral study showed a neutral response for both the sets of pictures. The mean relative power of alpha was observed to be elevated in left frontal region indicating negative emotion. Significant changes in mean relative beta power was observed between high valence high arousal stimuli ($\mathrm{F}3=0.01,\ \mathrm{F}4=0.016,\ \mathrm{F}7=0.013,\ \mathrm{F}8=0.007$) and neutral stimuli ($\mathrm{F}3=0.004,\ \mathrm{F}4=0.005,\ \mathrm{F}7=0.002,\ \mathrm{F}8=0.002$), indicating arousal though it is not perceived. Frontal alpha asymmetry scores, with the significance of $\mathrm{p} < 0.05$, showed withdrawal behavior while viewing the pictures when compared to rest. It is concluded that negative emotion for both neutral and positive stimuli could be a characteristic feature for Major Depressive Disorder.

I. Introduction

Major Depressive Disorder (MDD) is a mental health dysfunction identified by a persistent feeling of sadness, dejection, regret, lack of energy, fatigue, low self-esteem, low mood, low appetite, low sleep and lack of interest in pleasing routines. According to the statistics of WHO, nearly 57 million people in India are affected by depression which is 18 percentage of world estimate [1]. MDD is one of the important reasons for suicide. The death rate of depressed people is 1.52 times higher than the normal population. Emotion is a mental state that strongly influences one's thought and behavior. Depression is associated with the impairment of regulation of emotion [2], more specifically the suppression of positive emotion. Thus it is necessary to formulate a common pattern of brain activity that may be behind those feelings of low mood. This study focuses on the analysis of brain activity of the depressed people and understanding the emotional response towards positive stimuli when compared to neutral stimuli. The symptoms of depression are often known to get masked [3]. Thus, to get a better understanding of the actual emotional processing, perceived emotion using subjective scaling and induced emotion using Electroencephalography (EEG) are being studied.