Studies in 20 healthy right-handed subjects analyzed evoked EEG synchronization and desynchronization in the delta, theta1, theta2, alpha1, alpha2, beta1, beta2, beta3, and gamma ranges in response to sequential presentation of stimuli from the International Affective Picture System (IAPS) with low, medium, and high emotional activation impact. Each signal presentation was accompanied by subjective scaling of the extent of its emotional impact. EEG traces were recorded in 62 channels as signals were presented. These experiments showed that the degree of emotional impact of the signal was significantly associated with increases in evoked synchronization in the delta, theta1, theta2, beta1, beta3, and gamma ranges and with the effects of combined changes in evoked synchronization and desynchronization in the alpha2 frequency range. The interhemisphere distribution of evoked changes in power provided evidence that not only the posterior areas of the right hemisphere were involved in analyzing the emotional significance of images, as indicated by changes in evoked theta1 and theta2 synchronization and alpha2 desynchronization, but also the anterior areas of the left hemisphere, as indicated by changes in evoked theta2 synchronization. From the standpoint of affective chronometry, the earliest discrimination of the emotional content of stimuli, regardless of the sign of the emotion, occurred in the lower theta range and was seen at 0-600 msec after the start of stimulus presentation. This process was delayed 600-1000 msec in the theta2, alpha2, and gamma ranges.

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Studies on 30 right-handed subjects addressed EEG characteristics (62 channels) in conditions of laboratory simulation of induced emotions of happiness, joy, anger, disgust, fear/anxiety, and sadness. Induced emotions were found to produce, along with common features, individual patterns in the distribution of amplitude-frequency EEG characteristics. Induced positive and negative discrete emotions were characterized by interhemisphere activatory asymmetry in the theta-2 (4-6 Hz), alpha-2 (10-12 Hz), and beta-1 (12-18 Hz) ranges. Experience of the emotions of joy, anger, and disgust occurred on the background of asymmetrical increases in activity in the anterior cortex of the left hemisphere in the theta-2 range, suggesting a leading role for the activity of these areas in realizing the cognitive components of emotional reacting. In addition, some high-ergicity negative emotions evoked combined alpha-2 and beta-1 desynchronization (disgust) or beta-1 desynchronization (fear/anxiety) in the right parietal-temporal cortex, suggesting its involvement in the mechanisms of non-specific emotional activation. These data provide evidence that each of these emotions is characterized by its own individual pattern in the distribution of the amplitude-frequency characteristics of the EEG and, on the other hand, that series of ranges and cortical areas show similar but different (in terms of intensity) effects in response to emotional activation for emotions of different flavor.

Event-related desynchronization (ERD) and synchronization (ERS) in the individually defined theta, alpha-1, alpha-2, and alpha-3 frequency bands were measured in 22 healthy subjects (Ss) in response to neutral (Neut), emotionally positive (Pos), and negative (Neg) IAPS stimuli. The 62-channel EEG, facial EMG and ECG were simultaneously recorded while subjects viewed sequentially presented pictures and subjectively rated them after each presentation. The obtained findings indicate that differences induced by pictures varying in emotional valence are associated mainly with increased theta and alpha-3 synchronization activity and anterior hemispheric asymmetries. In the anterior temporal leads theta ERS revealed a significant valence by hemisphere interaction showing relatively greater right hemisphere theta ERS for Neg and left hemisphere ERS for Pos stimuli in the time window of 100-700 ms post-stimulus, whereas in the alpha-3 band Neg stimuli induced lateralized time-dependent left hemisphere ERS increased in the time window of 800-1200 ms, were not observed for Neut and Pos stimuli. The obtained results along with earlier observations on EEG correlates of affective processing challenge the notion that affective anterior hemispheric asymmetries are mainly sensitive to wide alpha frequency band. Frequency and time dependence of anterior hemispheric asymmetries in emotional valence discrimination is emphasized.