Valence-dependent changes in visual arousing elicitation: An exploratory study in EEG gamma oscillations

Emotion regulation involves several brain areas such as prefrontal cortex, amygdala, and insular cortex. However, considering different levels of arousing elicitations, how such a brain dynamics is affected by emotional pleasant/unpleasant (valence) elicitation is not fully understood. To this aim, we propose an Electroencephalographic (EEG)-based preliminary study in which 22 healthy subjects were elicited through affective pictures gathered from the International Affective Picture System. Considering 4 arousing levels, each of which including two valence levels (pleasant and unpleasant), we investigated EEG power spectra and functional connectivity. Focusing on gamma oscillations (> 32 Hz), because of their known sensitivity to valence changes, results revealed no significant changes between pleasant/unpleasant elicitation when lower and higher arousing level occurred. Conversely, valence changes in the intermediate arousing sessions were associated with changes in the prefrontal and occipital regions. Additionally, different arousing levels of pleasant elicitations affected short-range connectivity over the right hemisphere, whereas different arousing levels of unpleasant elicitations affected medium-range connectivity over the left hemisphere.