Научная статья на тему 'Alexithymia is associated with increased right hemispheric reactivity to emotional films: an EEG study'

Alexithymia is associated with increased right hemispheric reactivity to emotional films: an EEG study Текст научной статьи по специальности «Биотехнологии в медицине»

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Текст научной работы на тему «Alexithymia is associated with increased right hemispheric reactivity to emotional films: an EEG study»


Conference of Biological Psychiatry

«Stress and Behavior»

Proceedings of the 9th International Multidisciplinary Conference «Stress and behavior» Saint-Petersburg, Russia, 16-19 May 2005 Editor: Allan V. Kalueff, PhD





A.A. Varlamov, LJ. Aftanas State Research Institute of Physiology SB RAMS,

Novosibirsk, Russia

Over the past two decades there has been an expanding scientific interest in the regulation of emotion and in the impact of emotional impairments on mental and physical health. Alexithymia has in its basis difficulties in emotional self-regulation and is thought to a strong risk factor in a variety of medical and psychiatric disorders. Alexithymia construct is marked by the following features: 1) difficulty in identifying and describing feelings; 2) difficulties in distinguishing feelings from the bodily sensations of emotional arousal; 3) constricted imaginal capacities; 4) a tendency to focus on external events rather than inner experience. However the association of alexithymia with differences in brain oscillations and emotional regulation is still unclear. The main objective of the present study was to examine how alexithymia influences EEG rhythmic brain activity and hemispheric activation asymmetries during experience of positive and negative emotions evoked by watching specially designed short film clips. The 62-channels EEG was recorded in 27 non-alexithymic and 17 alexithymic participants viewing neutral and emotional film clips. Overall there were 10 film clips designed to induce different emotional states used in the experimental procedure: relaxation, joy, sexual arousal, anger, fear, disgust, sadness, emotional stress (different negative emotions of high intensity), and 2 emotionally neutral films serving as a control condition. All the film clips were in color, lasted 1.5 to 4.5 minutes and were followed by selfreport aimed to verify the success of emotional induction. After eliminating ocular and myographic artefacts three artefact free EEG segments by 8.192 s for each condition were fast Fourier transformed (FFT), averaged in the frequency domain, and then grouped into the delta (2—4 Hz), theta-1 (4—6 Hz), theta-2 (6—8 Hz), alpha-1 (8—10 Hz), alpha-2 (10—12 Hz), beta-1 (12—18 Hz), beta-2 (18—22 Hz), beta-3 (22—30 Hz), and gamma (30—45 Hz) frequency bands. The most pronounced between-group differences associated with film emotionality were evidenced for the erotic, anger, fear, and stress films. Only these films were retained for analyses. To specify group differences related to emotional manipulation each emotional film was contrasted with the neutral film condition. For each emotional film and each frequency band the ANOVAs with the factors of group, film condition, hemisphere and localization were computed with repeated measurements on the last three factors. Greenhouse-Geisser correction was applied where appropriate. Statistical analyses have not revealed any influence of alexithymia on the subjective report ratings of the experimental conditions. The observed effects of emotional stimulation were similar for both experimental groups and indicated that all the emotional films successfully elicited target emotions. In the neutral film condition EEG group differences were revealed only in the alpha-2 band and indicated that the alexithymics showed higher power values in right posterior regions, whereas the controls revealed no asymmetry (GRrHEMrLOC interaction, F(8.344) = 3.99, p < 0.004). Statistically significant EEG film-specific effects modulated by the alexithymia factor were found for the relaxation, erotic, anger, fear and stress films. Generally, there were two groups of effects, and for all the cases the alexithymics were characterized with increased emotional reactivity of anterior or posterior cortical regions. First, the alexithymics have revealed an emotion-related increase of slow rhythmic activity over right anterior cortical regions for relaxation (theta-2 band), anger (theta-2) and stress (delta) films in

ISSN 1606-8181

comparison to the control group (the largest p < 0.013, detailed statistical data are omitted for the sake of brevity). Second, the alexithymics have shown an emotion-related decrease power in lower and upper alpha bands over right posterior cortical regions for erotic (alpha-2), fear (alpha-2), anger (alpha-2) and stress (alpha-1 and alpha-2) films vs. controls (max. p < 0.027). Interpreting the obtained results and basing on the functions of specific cortical regions and frequency bands we can imply that the increase of slow rhythmic activity over right anterior regions found in alexithymics can point to increased negative affect and activation of withdrawal motivational tendency; such an interpretation corresponds to experimental psychology findings. The activation (decrease of alpha power) of right posterior regions during emotional processing can indicate increased ‘cortical effort’ of alexithymics and mobilization of additional right-hemispheric resources. In view of the modern concepts such an effort may be necessary to overcome difficulties in symbolization of the arisen emotional state, resulting from deficient referential process and associated with right-hemispheric analogical and global nonverbal representation.

ISSN 1606-8181

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