Analysis of Brain Reaction to Emotional Faces

Abstract

This work is aimed to study the changes of the emotion-induced variations in the brain's electrical activity. We focused on revealing alterations in cognitive mechanisms caused by the presentation of neutral human face stimuli among faces with either negative or positive expressions. To access the changes, Fourier Power Spectral Density (PSD) and the scaling exponent values obtained from the detrended moving average analysis (DMA) were compared in seven frequency ranges for the series when emotionally neutral stimuli were presented after positive and negative images of human faces. As a result, the cortical mapping of the evoked responses was obtained and analyzed to reveal the manifestations of the specific brain activity. Sex-related differences consisted of activating two major cognitive networks of the brain: emotional or theta-network and cognitive beta-network. As for cortical topography, PSD changes occurred in the antero-central areas of the cortex in the $\boldsymbol{\theta 1}$-subband (extension of working memory) and almost generally within all the cortical areas in the $\boldsymbol{\beta 1}$-subband (activation of external attention). Analysis conducted between male and female groups showed that the most significant changes were found in the female group during the processing of neutral images under the negative stimuli aftereffect. The DMA analysis revealed a greater synchronization of oscillations in the 01-range in the left frontal-temporal zones in the case of neutral image presentation preceded by positive stimuli. Apart from that, in the series of neutral image presentation against the negative emotional background, the female group was characterized by maintaining a high level of long-range spatio-temporal correlations of the electroencephalogram signal in the central and right temporal-occipital areas.