Comparing three models of arousal in the human brain.

The bipolar valence-arousal model is assumed by many to be an underlying structure of conscious experience of core affect and emotion. In this work, we compare three versions of the bipolar valence-arousal model at the neural domain, using functional magnetic resonance imaging (fMRI). Specifically, we systematically contrast three models of arousal: model 1-'arousal as a separate quale from valence', model 2-'arousal as intensity of bipolar valence' and model 3-'arousal as a linear combination of unipolar pleasant and unpleasant'. Using parametric modulation analysis, we estimated the ability of each model to predict activation in arousal-related brain regions, in response to affective stimuli. The results suggest that arousal is not separable from valence in its ability to predict arousal-related neural activity. The relevance of the results to the theory of conscious affect is discussed.