Abstract
High-frequency electroencephalography (EEG) signals play an important role in research on human emotions. However, the different network patterns under different emotional states in the high gamma band (50–80 Hz) remain unclear. In this paper, we investigate different emotional states using functional network analysis on various frequency bands. We constructed multiple functional networks on different frequency bands and performed functional network analysis and time–frequency analysis on these frequency bands to determine the significant features that represent different emotional states. Furthermore, we verified the effectiveness of these features by using them in emotion recognition. Our experimental results revealed that the network connections in the high gamma band with significant differences among the positive, neutral, and negative emotional states were much denser than the network connections in the other frequency bands. The connections mainly occurred in the left prefrontal, left temporal, parietal, and occipital regions. Moreover, long-distance connections with significant differences among the emotional states were observed in the high frequency bands, particularly in the high gamma band. Additionally, high gamma band fusion features derived from the global efficiency, network connections, and differential entropies achieved the highest classification accuracies for both our dataset and the public dataset. These results are consistent with literature and provide further evidence that high gamma band EEG signals are more sensitive and effective than the EEG signals in other frequency bands in studying human affective perception.
Highlights
Emotions play an important role in our daily life; they are involved in cognitive processes such as memory, learning, and decision-making (Zhang et al, 2015)
The valence and the arousal ratings of all subjects were averaged, and the rating scores of different stimulus groups were compared by post-hoc analysis; the test results were corrected by using false discovery rate (FDR)
We discovered that the differential entropies (DEs) distribution with significant differences mainly existed in the high frequency bands, and most of the electrodes with significant differences were in the high gamma band
Summary
Emotions play an important role in our daily life; they are involved in cognitive processes such as memory, learning, and decision-making (Zhang et al, 2015). The studies on neuroscience, psychology, and cognitive science show that physiological signals can reflect human emotional states (Dan, 2012). High-frequency-band (>30 Hz) activities reflect the characteristics of emotional integration (Matsumoto et al, 2010); in particular, high gamma band (50– 70 Hz) plays an important role in the cognitive control of emotions (Tang et al, 2011). A similar response to affective pictures in high frequency bands has been observed in studies using invasive intracranial EEG signals; researchers found that emotional pictures are associated with replicable modulations of broadband high gamma band (70– 150 Hz) invasive intracranial EEG signals. Unpleasant stimuli elicit a stronger response in the lateral–occipital and occipital– temporal areas than neutral stimuli, and pleasant pictures elicit stronger responses than other stimuli in the high gamma band (Boucher et al, 2014)
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