Abstract
Aim: The research aimed to study and model the emotion-related activity of functional networks within the human brain cortex using power spectrum density and detrended phase transfer entropy methods. Attention was focused on revealing alterations in cognitive mechanisms, caused by presentation of neutral human faces as rare stimuli among faces with either negative or positive expression. Methods: EEG-data was recorded during the perception and processing of neutral human facial expressions, presented among positive and negative faces in two series of images, alongside with resting state with open and closed eyes, which was further analyzed using power spectrum density and detrended phase transfer entropy methods. Results: Specific EEG-bands (θ and β) were chosen for the analysis based on their prominent role in memory- and emotion-related mechanisms. The topography of the spectral power density corresponded to the generally accepted ideas describing perception and visual stimuli processing mechanisms. The phase transfer entropy method was not sufficient to analyze resting state data. The results of the analysis performed using the phase transfer entropy method revealed the problems of neutral faces differentiation when presented in a positive emotional context. Simultaneously, enhanced processes of motivational coding and self-reflection were observed during the presentation of neutral faces in a negative emotional context. These results corresponded with the data obtained in our previous ERP-based study. Conclusions: Phase transfer entropy and spectral power density have demonstrated their effectiveness in analyzing the mechanisms of emotional visual stimuli processing mediated in different cortical areas.
Highlights
Human facial expressions are complex multi-dimensional visual stimuli, which provide the brain with a wide range of characteristics to process
Eyes opening caused the spread of generalized activation around the cortex, covering occipital and parietal, central, and frontal areas of the cortex, with right-hemisphere lateralization in temporal regions
Results obtained with phase Transfer entropy (TE) during resting states with both closed and open eyes were generally close to zero, which supports the view that this analysis method is suitable for mapping brain networks associated with a specific cognitive task
Summary
Human facial expressions are complex multi-dimensional visual stimuli, which provide the brain with a wide range of characteristics to process. In our previously conducted ERP study, we have revealed that the stimuli' valence, which creates the emotional context for the target neutral expressions, affects perception. This effect is signified in the increase of attention level and memory processes [4]. To reveal and quantify "causal" or directional inter-areal phase-phase interactions during emotion perception, a new information theory-based approach of phase transfer entropy (phase TE) was used, as phase synchronization of neuronal-based oscillations has been suggested to determine the coordination and integration of anatomically distributed information processing [5]. That is why the weed control issues demand new ways of solving
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