1. Time-dependent cortical asymmetries induced by emotional arousal
EEG analysis of event-related
synchronization and desynchronization in
Individually defined frequency bands
Ljubomir I. Aftanas, Anton A. Varlamov, Sergey V. Pavlov,
Viktor P. Makhnev, Natalya V. Reva 2001
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

2. Questions raised by the article:
Do interhemispheric asymmetries, emerging during affective processing and indexed by ERD/ERS measures, vary with the judged arousal of an affective picture foreground?
If so, when, where and at which frequencies does this occur?
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

3. The experiment
International Affective Picture System (IAPS) stimuli with low, moderate and high arousal (LA, MA and HA) content,
62-channel EEG,
Skin Conductance Response (SCR),
Heart Rate (HR).
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

4. The experiment
Participants are instructed to attend to the pictures, No overt response is required, to keep inherent affective reactions to these stimuli.
Event-related desynchronization (ERD) and synchronization (ERS)
theta and alpha frequency band was measured
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

5. Sequence of one experimental trial
Blank screen then small cross for 4s
Presentation of a picture for 6s
Total length of EEG epoch recorded : 12s (5s before and 7s after picture onset)
The IAPS stimuli are subjectively rated using the Self-Assessment Manikin
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

6. Arousal / Valence
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

7. IAPS Stimuli
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

8. Self-Assessment Manikin (SAM)
Pleasure
Arousal
Dominance
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

9. Results
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

10. Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

11. Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

12. Results
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

13. Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

14. Results
Theta, alpha-1 and alpha-3 bands : effects of arousal discrimination.
Theta and alpha-3 bands : association with hemispheric asymmetries in the anterior /posterior direction of the cortical plane.
Discriminative properties of theta synchronization in the time period of ms post-stimulus.
In the alpha-1 and alpha-3 bands, discriminative process : ms.
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

15. Conclusions
The skin conductance and heart rate data provided important support that picture differences are attributable to emotional arousal.
Affective processing seems to be frequency- dependent, the theta oscillating networks were the fastest in affect discrimination.
Time-dependence of hemispheric asymmetries induced by affective processing.
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

16. Conclusions
Posterior regions of the right hemisphere involved in the modulation of emotion-related arousal (theta and alpha-3 bands).
Anterior regions of the left hemisphere (theta and alpha-3 bands) : valence dimension.
Are there really hemispheric asymmetries ?
There is no physiological facts which assert the existence of an asymmetry in the emotional expression.
Seminar BCI - Presentation – Adrien Cognée – March 12th 2009

17. Thanks