Exploratory Cross-Frequency Coupling and Scaling Analysis of Neuronal Oscillations Stimulated by Emotional Images: An Evidence From EEG

Emotion as a physiological state, plays an important role in neuroscience, cognitive science, rational thinking, decision making, and mental states. Therefore, how to quantitatively analyze the different emotion state is especially important. The traditional manner through the spectral power and amplitude of a certain frequency, which reflects the strength of local cortical activation. Cross-frequency coupling (CFC) and self-affinity are observed neural phenomena associated with cognitive processes. This measures, differ across brain areas and frequency bands in a task-relevant manner, changing quickly in response to cognitive events, motor actions, and correlates with emotion. In this study, the electroencephalogram (EEG) signals of all participants in response to stimulation were collected using a 64-channel amplifier recording system. 'Exploratory CFC and scaling analysis' were applied to four different categories of emotions, including depression, relaxation, fear, and happiness. Three phase-amplitude coupling (PAC) indices [The Kullback-Leibler-based modulation index (KL-MI), the mean vector length modulation index (MVL-MI), and the phase-locking value (PLV)] and four scaling indices (Amplitude analysis, detrended fluctuation analysis (DFA), life-times, and waiting-times analysis) were introduced and calculated to find out the difference of each emotion. The results suggested that α and β rhythm had a distinct coupling effect with high- γ rhythm; furthermore, the prefrontal and temporal lobes were the main contributors to the value of PAC, which provides a theoretical basis for PAC to regulate the emotional process. These results indicate that the feasibility of a new method for emotional computing and have huge prospects in auxiliary diagnosis.