Erotic and disgust-inducing pictures—Differences in the hemodynamic responses of the brain Rudolf Stark a,b, * , Anne Schienle a,b , Cornelia Girod a , Bertram Walter b , Peter Kirsch a,b , Carlo Blecker b , Ulrich Ott b , Axel Scha¨fer a,b , Gebhard Sammer b , Mark Zimmermann a,b , Dieter Vaitl a,b a Department of Clinical and Physiological Psychology, Justus-Liebig-University of Giessen, Otto-Behaghel-Str. 10, 35394 Giessen, Germany b Bender Institute of Neuroimaging at the Justus-Liebig-University of Giessen, 35394 Giessen, Germany Received 1 February 2004; accepted 26 November 2004 Available online 15 February 2005 Abstract The aim of this fMRI study was to explore brain structures that are involved in the processing of erotic and disgust-inducing pictures. The stimuli were chosen to trigger approach and withdrawal tendencies, respectively. By adding sadomasochistic (SM) scenes to the design and examining 12 subjects with and 12 subjects without sadomasochistic preferences, we introduced a picture category that induced erotic pleasure in one sample and disgust in the other sample. Since we also presented neutral pictures, all subjects viewed pictures of four different categories: neutral, disgust-inducing, erotic, and SM erotic pictures. The analysis indicated that several brain structures are commonly involved in the processing of disgust-inducing and erotic pictures (occipital cortex, hippocampus, thalamus, and the amygdala). The ventral striatum was specifically activated when subjects saw highly sexually arousing pictures. This indicates the involvement of the human reward system during the processing of visual erotica. # 2005 Elsevier B.V. All rights reserved. Keywords: fMRI; Emotion; Disgust; Pleasure; Sex behavior; Ventral striatum; Reward system 1. Introduction Modern brain imaging techniques like functional magnetic resonance imaging (fMRI) provide new insights into the functioning of emotion-relevant brain structures and can therefore help to improve contemporary models of affective processing. In many current biological theories of emotion the existence of at least two motivational systems is proposed: an approach and a withdrawal system (Arnold, 1960; Konorski, 1967; Lang et al., 1990; Davidson et al., 2000). The approach system responds to stimuli, which promote the survival of the species (e.g. food-related or sexual stimuli), whereas the withdrawal or defense system is triggered by stimuli, which threaten the personal integrity (e.g. fear- inducing or disgust-inducing stimuli). It is still under discussion how these systems are represented in the brain. While some theories suggest the existence of central structures, which are involved in both, the decision of whether something is good (and therefore should be approached), and the decision of whether something is bad (and therefore should be avoided), other theories assume a selective responsiveness of certain brain areas to either positive or negative stimuli. For example, Rolls (1999) describes the amygdala together with the orbitofrontal cortex as an entity, which decodes the salience of a stimulus independent of its valence. In contrast, Gray (1994) suggests a dissociation of brain structures involved in behavioral inhibition and approach. Davidson and Irwin (1999) also postulate a valence-specific topography of emotional processing in the form of a frontal asymmetry. www.elsevier.com/locate/biopsycho Biological Psychology 70 (2005) 19–29 * Corresponding author. Tel.: +49 641 9926082; fax: +49 641 9926099. E-mail address: rudolf.stark@psychol.uni-giessen.de (R. Stark). 0301-0511/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.biopsycho.2004.11.014