Abstract
Repetitive transcranial magnetic stimulation (rTMS) can serve as a tool to experimentally test hypotheses of prefrontal cortex (PFC) modulation of emotions. This is important to understand the significance of PFC dysfunction observed in affective disorders, e.g. major depression. Proceeding from the valence model of emotions, the present study used rTMS to test the hemispheric lateralization of both self-rated mood and emotionally induced facial expressions. Nine healthy volunteers were stimulated with 10 Hz rTMS at the left and right PFC, in random order. Visual analog scales (VAS) were used for subjective mood-ratings. Facial expressions (laughing) were assessed by a computerized three-dimensional movement analysis system (CMS 70, ZEBRIS) with high temporal and spatial resolution during a humorous movie. Changes of VAS scores showed no difference between both stimulation sites. Facial expression analysis revealed selective effects of left and right prefrontal stimulation. The frequency of laughing reactions was significantly increased and the emotional reaction time significantly shortened after left compared to right prefrontal rTMS. In conclusion, facial expression analysis can detect lateralized changes of emotional reactions after rTMS which do not correspond to changes of subjective measures. We propose to combine rTMS and facial expression analysis for further studies of the cortical modulation of emotions in man.
Published Version
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