Affective pictures processing is reflected by an increased long-distance EEG connectivity

Abstract

Analysis of affective picture processing by means of EEG has invaded the literature. The methodology of event-related EEG coherence is one of the essential methods used to analyze functional connectivity. The aims of the present study are to find out the long range EEG connectivity changes in perception of different affective pictures and analyze gender differences in these long range connected networks. EEGs of 28 healthy subjects (14 female) were recorded at 32 locations. The participants passively viewed emotional pictures (IAPS, unpleasant, pleasant, neutral). The long-distance intra-hemispheric event-related coherence was analyzed for delta (1-3.5 Hz), theta (4-7.5 Hz), and alpha (8-13 Hz) frequency ranges for F₃-T₇, F₄-T₈, F₃-TP₇, F₄-TP₈, F₃-P₃, F₄-P₄, F₃-O₁, F₄-O₂, C₃-O₁, C₄-O₂ electrode pairs. Unpleasant pictures elicited significantly higher delta coherence values than neutral pictures (p < 0.05), over fronto-parietal, fronto-occipital, and centro-occipital electrode pairs. Furthermore, unpleasant pictures elicited higher theta coherence values than pleasant (p < 0.05) and neutral pictures (p < 0.05). The present study showed that female subjects had higher delta (p < 0.05) and theta (p < 0.05) coherence values than male subjects. This difference was observed more for emotional pictures than for neutral pictures. This study showed that the brain connectivity was higher during emotional pictures than neutral pictures. Females had higher connectivity between different parts of the brain than males during emotional processes. According to these results, we may comment that increased valence and arousal caused increased brain activity. It seems that not just single sources but functional networks were also activated during perception of emotional pictures.

Keywords: EEG; EEG connectivity; Emotion; Event related coherence; Gender; IAPS.

Fig. 1

Grand average of event-related coherences for F₄–P₄ electrode pair upon application of unpleasant, pleasant, and neutral IAPS pictures. Red line indicates unpleasant pictures, blue line indicates pleasant pictures, and black line indicates neutral pictures. (Color figure online)

Fig. 2

Grand average of event-related coherences for F₄–O₂ electrode pair upon application of unpleasant, pleasant, and neutral IAPS pictures. Red line indicates unpleasant pictures, blue line indicates pleasant pictures, and black line indicates neutral pictures. (Color figure online)

Fig. 3

Grand average of event-related coherences for C₄–O₂ electrode pair upon application of unpleasant, pleasant, and neutral IAPS pictures. Red line indicates unpleasant pictures, blue line indicates pleasant pictures, and black line indicates neutral pictures. (Color figure online)

Fig. 4

Grand average of event-related coherences for F₄–P₄ electrode pair for male and female upon application of unpleasant (a), pleasant (b), and neutral (c) IAPS pictures. Dashed line indicates male participants, and bold line indicates female participants

Fig. 5

Grand average of event-related coherences for C₄–O₂ electrode pair for male and female upon application of unpleasant (a), pleasant (b), and neutral (c) IAPS pictures. Dashed line indicates male participants, and bold line indicates female participants

Fig. 6

The mean delta coherence values upon presentation of unpleasant, pleasant, and neutral pictures. Solid line represents the mean delta coherence values for females, and dashed line represents the mean delta coherence values for males. Vertical bars denote ±standard errors

Fig. 7

Diagrams for event related oscillatory responses (delta, theta, alpha, beta and gamma) upon presentation of unpleasant pictures. The diagram was shaped according to the results of previous studies (Balconi et al. ; Güntekin and Basar , ; Güntekin and Tülay ; Klados et al. ; Woodruff et al. 2011)

Fig. 8

Schematic representation of results of delta and theta coherence for the unpleasant picture processing