Contents lists available at ScienceDirect Psychiatry Research: Neuroimaging journal homepage: www.elsevier.com/locate/psychresns Individual OCD-provoking stimuli activate disorder-related and self-related neuronal networks in fMRI Kathrin Viol a,b, ⁎ , Benjamin Aas a,b,c , Anna Kastinger a,b , Martin Kronbichler d,e , Helmut Schöller a,b,c , Eva-Maria Reiter f , Sarah Said-Yürekli d,e,g , Lisa Kronbichler d,e , Brigitte Kravanja-Spannberger b , Barbara Stöger-Schmidinger b , Wolfgang Aichhorn a,b , Günter Schiepek a,b,c a Institute of Synergetics and Psychotherapy Research, Paracelsus Medical University, Salzburg, Austria b Department of Psychosomatics and Inpatient Psychotherapy, University Hospital for Psychiatry, Psychotherapy and Psychosomatics, Paracelsus Medical University, Salzburg, Austria c Department of Psychology, Ludwig Maximilians University, Munich, Germany d Centre for Cognitive Neuroscience and Department of Psychology, Paris Lodron University of Salzburg, Salzburg, Austria e Neuroscience Institute, Christian-Doppler Medical Center, Paracelsus Medical University, Salzburg, Austria f Department for Radiotherapy and Radio-Oncology, Christian-Doppler University Hospital of the Paracelsus Medical University, Salzburg, Austria g Department for Neurology, Christian-Doppler University Hospital of the Paracelsus Medical University, Salzburg, Austria ARTICLE INFO Keywords: Symptom provocation Individualized stimuli Standardized stimuli MOCSS Cortical midline structure ABSTRACT For patients with Obsessive-Compulsive Disorder (OCD), whose triggers are highly idiosyncratic, individual stimulus material has been used in several fMRI studies. This study aims at comparing individual to standardized picture sets and at investigating a possible overlap of the former with the self-referential neuronal network. During fMRI-scanning, 17 inpatients with OCD and 17 healthy controls were exposed to pictures of their per- sonal triggers, photographed in their domestic environments, to standardized pictures designed to provoke OCD symptoms, and to neutral pictures. Whole-brain analyses were calculated and the pictures were rated by both patients and controls with respect to valence, arousal, and coping. Patients rated the individualized stimuli lower in valence and coping and higher in arousal compared to controls, and also compared to standardized OCD- and neutral stimuli. The individual stimuli elicited neuronal activity in the cingulate cortex, hippocampus, insula, middle frontal/precentral gyrus, superior/inferior parietal lobe, and precuneus, while no group difference was detected by the standardized OCD-stimuli. In conclusion, individual picture sets facilitate the detection of neuronal activity, but the results might be confounded due to the overlap with the network of self-referential processing and memory retrieval. The use of individual symptom-provoking and individual neutral stimuli would therefore be optimal. 1. Introduction 1.1. Importance of stimuli for fMRI Choosing the right stimulus material is highly relevant in fMRI re- search in order to answer the hypotheses under investigation. In studies aimed at examining neuronal correlates for psychiatric disorders, pa- tients are usually confronted with disorder-specific triggers in the imaging environment, e.g., by passively viewing pictures designed to evoke symptom-related emotions and cognitions. The BOLD-signal of the fMRI scan, however, is composed of a baseline neuronal activity (comparable to resting-state activity), plus the activity due to visual processes when viewing pictures of any kind, plus the activity representing the neuropathological mechanisms of a disorder. Therefore, most analyses use contrasts of two conditions by subtracting the measured signal when viewing the symptom provoking pictures (condition 1) from the measured signal when viewing neutral pictures (condition 2). The difference (contrast) can then be interpreted as the neuronal activity evoked by specific aspects of condition 2 in compar- ison to condition 1 (e.g., disgust-provoking stimuli). The same proce- dure is conducted for all participants, and the averages for each group (patients and controls) are calculated. The difference between patients and controls can then be determined by subtracting the mean contrast of the controls from the mean contrast of the patients. The remaining signal can be interpreted as the pathological activity. Considering this procedure of analysis, it becomes clear that the choice of stimulus https://doi.org/10.1016/j.pscychresns.2018.12.008 Received 31 August 2018; Received in revised form 11 December 2018; Accepted 11 December 2018 ⁎ Corresponding author. E-mail address: k.viol@salk.at (K. Viol). Psychiatry Research: Neuroimaging 283 (2019) 135–144 Available online 14 December 2018 0925-4927/ © 2018 Elsevier B.V. All rights reserved. T