Impact of Valence and Age on Olfactory Induced Brain Activation in Healthy Women Martina Reske RWTH Aachen University, Forschungszentrum Juelich, University of California San Diego, and JARA-BRAIN– Translational Brain Medicine Thilo Kellermann RWTH Aachen University and JARA-BRAIN–Translational Brain Medicine N. Jon Shah Forschungszentrum Juelich JARA-BRAIN–Translational Brain Medicine, and RWTH Aachen University Frank Schneider and Ute Habel RWTH Aachen University and JARA-BRAIN–Translational Brain Medicine The aim of the present study was to assess the effect of age on cerebral correlates of olfactory induced negative emotions. We investigated 15 healthy women (aged 21– 47) in a functional MRI (fMRI) study during passive smelling of one negative odor (rotten yeast) and two control conditions presenting a neutral odor (vanilla) and odorless ambient air. Besides odor-specific differences in ratings of valence (yeast less pleasant than vanilla and air), intensity (yeast more intense than vanilla and air), and arousal (yeast more arousing than vanilla and air), self-ratings verified the intended mood induction effect: subjects experienced more disgust during yeast stimulation compared to ambient air and vanilla. Along with the superior temporal cortex, medial, and lateral orbitofrontal activations were found to discriminate between negative and neutral olfactory stimulation (yeast and vanilla) directly. Activations of the dorsolateral prefrontal cortex and the caudate were correlated with age and showed stronger valence- related responses (yeast vs. vanilla) in younger compared to older women. Stronger BOLD signals within the anterior cingulate gyrus, insula and motor areas were found during negative compared to neutral stimulation and are considered to represent an attempt to down-regulate the strong emotional experience and the organisms’ preparation for withdrawal, respectively. Our results stress the role of orbitofrontal and superior temporal brain regions in odor-related valence coding and stress the necessity to consider age as a modulating factor for further studies, even in relatively young samples. Keywords: fMRI, olfaction, emotion, valence, age The olfactory system combines phylogenetically old and new brain areas. Concerning its neuroanatomical structure it is unique in its predominant access of ipsilateral brain regions. Additional contralateral projections via the anterior commissure have also been described (Savic & Gulyas, 2000). Olfactory afferences reach the piriform and entorhinal cortex, thalamus, hypothalamus, and the limbic amygdala and project to the orbitofrontal cortex (OFC). Imaging studies using olfactory stimuli found a network activated among others including the piriform-amygdala region, the OFC, insula, superior temporal gyrus, and the anterior cingulate cortex (ACC). Activations within the primary olfactory (piriform) and orbitofrontal cortex have only been reported inconsistently, a fact which can be related to habituation processes (Sobel et al., 2000). Additionally, these regions are close to air/tissue interfaces and therefore are prone to susceptibility artifacts. The olfactory system is the only human sensory system display- ing direct connections to the amygdala which implicates its close access to emotional processes. Accordingly, olfactory stimulation turned out to be an effective method for mood induction (Chen & Haviland-Jones, 1999; Schneider et al., 2007; Koch et al., 2007). The perceptual processing of emotions and odors is dominated by its hedonic characteristic (pleasantness— unpleasantness). The neural networks of emotions have been examined intensively while the joint and distinct neural representations of different basic emotions have only recently been investigated. Meta-analyses found indications for both, common and emotion specific activa- Martina Reske, Department of Psychiatry and Psychotherapy, RWTH Aachen University, Institute of Neuroscience and Medicine - 4, Forschung- szentrum Ju ¨lich GmbH, Department of Psychiatry, University of California San Diego, and JARA-BRAIN–Translational Brain Medicine; Thilo Keller- mann, Department of Psychiatry and Psychotherapy, RWTH Aachen Univer- sity and JARA-BRAIN–Translational Brain Medicine; N. Jon Shah, Institute of Neuroscience and Medicine - 4, Forschungszentrum Ju ¨lich GmbH, Depart- ment of Neurology, RWTH Aachen University and JARA-BRAIN– Translational Brain Medicine, RWTH Aachen University; Frank Schneider and Ute Habel, Department of Psychiatry and Psychotherapy, RWTH Aachen University and JARA-BRAIN–Translational Brain Medicine. The MRI facility in Ju ¨lich was supported by the German Federal Ministry for Education and Research (BMBF; Grant 01 GO 0104). We gratefully acknowledge the participation of all our volunteers. We thank V. Backes, B. Elghahwagi, P. Engels, K. Koch, N.Y. Seiferth, and Sabrina Weber for assistance during data acquisition and data analysis (V. Backes). Correspondence concerning this article should be addressed to Martina Reske, Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich, 52425 Juelich, Germany. E-mail: m.reske@fz-juelich.de Behavioral Neuroscience © 2010 American Psychological Association 2010, Vol. ●●, No. ●, 000–000 0735-7044/10/$12.00 DOI: 10.1037/a0019289 1 AQ: 1 tapraid5/zeh-bne/zeh-bne/zeh00310/zeh2532d10z xppws S=1 4/29/10 7:23 Art: 2009-0471