Assessing Neural Oscillations during Erotic and Negative Emotional Pictures Viewing: An Event-Related Potential Study

The present study was designed to determine whether or not there are components of the ERPs that discriminate the erotic and negative pictures during affective picture processing. Participants viewed erotic, negative and neutral pictures form the International Affective Picture System (IAPS). Eighteen right-handed volunteer students from North-Eastern University participated in the experiment. Electrode from the frontal site (F3 and F4), C3 and C4 (central electrodes), P3 andP4 (parietal electrodes) and O1 and O2 (occipital electrodes) were averaged with the stimuli type and brain hemisphere. The change in spectral power of the brain signal and its main spectral bands of theta (3-7.5 Hz), Alpha (7.5-13 Hz) and Beta (13-25 Hz) were analyzed. Erotic stimuli showed ERP components deflected more negatively at the frontal electrode site than the negative picture stimuli during the time window of 200-300 ms whereas the negative valence stimuli processing reflected a positively twisted amplitude at the time window of 120-300 ms. The erotic and negative valence emotional picture stimuli show a significant difference in the spectral power of theta, alpha and beta frequency bands for the left vs. right hemisphere and frontal vs. occipital sites. Nonetheless, the time-frequency plots show us those emotionally valence visual stimuli triggered an increase of alpha band (7.5-13 Hz).