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- IfB - Institut für Bioengineering (2) (remove)
Background: One of the most prominent neurobiological
models of alexithymia assumes an altered function of the
anterior cingulate cortex (ACC) as the crucial neural correlate
of alexithymia. So far functional imaging studies have yielded
inconclusive results. Therefore, we tested this hypothesis
in healthy alexithymics and nonalexithymics in an event-related
fMRI study. Methods: Thirty high- and 30 low-alexithymic
right-handed male subjects (selected by the 20-item
Toronto Alexithymia Scale, TAS-20) were investigated with
event-related fMRI using a picture viewing paradigm. The
stimuli consisted of happy, fearful and neutral facial expressions
(Ekman-Friesen) as well as positive, negative and neutral
pictures from the International Affective Picture System.
Results: Contrasting the high-alexithymic with the low-alexithymic
group we observed increased activation of the supragenual
ACC for different emotional valences as well as for different emotional stimuli. Moreover, there was a positive
correlation of the ACC with the individual TAS-20 scores but
no correlations with the individual Beck Depression Inventory
scores. Additionally, there was no difference in activity
of the amygdala. Conclusions: We demonstrated that the
supragenual ACC is constantly activated more strongly in
alexithymic subjects and that this activation is related to the
symptoms of alexithymia and not to associated symptoms
such as depression. Therefore, our findings support the hypothesis
of an altered function of the ACC in alexithymia.
Differential modulation of valence and arousal in high-alexithymic and low-alexithymic individuals
(2010)
High-alexithymic individuals are characterized by an impaired ability to identify and communicate emotions whereas low-alexithymic individuals have a wide-ranging ability to deal with emotions. This study examined the hypothesis that valence and arousal modifications of emotional stimuli differentially modulate cortical regions in high-alexithymic and low-alexithymic individuals. To this end, 28 high-alexithymic and 25 low-alexithymic individuals were investigated with event-related fMRI using visual emotional stimuli. We found differential neural activations in the dorsal anterior cingulate, the insula and the amygdala. We suggest that these differences may account for the impaired ability of high-alexithymic individuals to appropriately handle emotional stimuli.