Nordt, M. 1 , Keuper, K. 1 , Zwanzger, P. 2 & Dobel, C. 1
1 Institute for Biomagnetism and Biosignalanalysis, University of Muenster
2 Department of Psychiatry, University of Muenster
The ‘early posterior negativity’ (EPN; 200-300 ms) reflects prioritized processing of emotional stimuli. It was recently discovered, that the EPN also appears in response to emotional words (Kissler et al., 2007). The question if the EPN in words is triggered by valence properties or by arousal hasn’t been settled yet. The present study aimed at investigating this topic by means of an extended combination of methods. Simultaneous EEG-MEG measurements were conducted while participants silently read continuously presented streams of neutral, positive and negative nouns. Data were analyzed using L2 minimum norm solutions based on individual head models and cortical constraints. For the time window of 200-300ms we found enhanced activation for emotional words in left occipito-temporal regions replicating the results of Kissler et al. (2007). Furthermore our results displayed activation in the cingulate cortex, consistent with fMRI studies on emotional word processing (Maddock et al., 2003). With regard to the valence of stimuli, we found more right dorsolateral prefrontal activity for negative words and more left inferior prefrontal activity for positive words. This supports early hemispheric specialization for valence differences of emotional stimuli (e.g. Davidson, 2001). Methodologically, this study emphasizes the benefit of combined neurophysiological measures.