Time-dependent cortical asymmetries induced by emotional arousalEEG analysis of event-relatedsynchronization 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

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

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

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

Sequence of one experimental trial

Blank screen then small cross for 4s

Presentation of a picture for 6sTotal length of EEG epoch

recorded : 12s (5s before and 7s after picture onset)

The IAPS stimuli are subjectively rated using the Self-Assessment ManikinSeminar BCI - Presentation – Adrien Cognée – March 12th 2009

Arousal / Valence

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

IAPS Stimuli

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

Self-Assessment Manikin (SAM)

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

Pleasure

Arousal

Dominance

Results

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

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

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

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

Results

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

ResultsTheta, 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 100-700ms post-stimulus.

In the alpha-1 and alpha-3 bands, discriminative process : 800-1200ms.

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

ConclusionsThe 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

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

Thanks