Narrow-band spectral measurements of EEG during emotional tasks

The objective of this study was to discover how narrow-band spectral measurements express emotional behavior. Electroencephalographic narrowband absolute and relative spectral powers were calculated for every 1 Hz of frequency from the recordings of 40 healthy male university students during emotional tasks. Sentences evoking positive, negative, and neutral emotional states were used as stimuli. Repeated multivariate analyses of variance were computed with IQ as covariate. The results showed only a few significant relations between absolute power and emotion. Relative power reflected better the differences determined by emotional states. The frequencies between 7.6 and 9.5 Hz showed differences between emotional states over the entire scalp with increased power during neutral state. Interaction between emotional states and cerebral regions revealed that all cerebral areas had an important role, especially frontal, parietal, and temporal regions. Hemispheric differences showed less power in the left hemisphere during positive emotional state (joy of love) in the 8.6 to 9.5 Hz band and in the right hemisphere during negative emotional state (frustration) in the 17.6 to 18.5 Hz band. Significant interaction between states, hemispheres, and electrode positions was observed in the frequency range of 17.6 to 19.5 Hz. As none of our results covered the range of any broad band, we may conclude that narrow-band calculations are more adequate for the study of emotions, because their use reduces the danger that frequency-specific effects go undetected or cancel each other.