ORIGINAL ARTICLE Functional Cliques in the Amygdala and Related Brain Networks Driven by Fear Assessment Acquired During Movie Viewing Sivan Kinreich, 1,2 Nathan Intrator, 3 and Talma Hendler 1,2,4 Abstract One of the greatest challenges involved in studying the brain mechanisms of fear is capturing the individual’s unique instantaneous experience. Brain imaging studies to date commonly sacrifice valuable information regard- ing the individual real-time conscious experience, especially when focusing on elucidating the amygdala’s activ- ity. Here, we assumed that by using a minimally intrusive cue along with applying a robust clustering approach to probe the amygdala, it would be possible to rate fear in real time and to derive the related network of activation. During functional magnetic resonance imaging scanning, healthy volunteers viewed two excerpts from horror movies and were periodically auditory cued to rate their instantaneous experience of ‘‘I’m scared.’’ Using graph theory and community mathematical concepts, data-driven clustering of the fear-related functional cliques in the amygdala was performed guided by the individually marked periods of heightened fear. Individually tai- lored functions derived from these amygdala activation cliques were subsequently applied as general linear model predictors to a whole-brain analysis to reveal the correlated networks. Our results suggest that by using a localized robust clustering approach, it is possible to probe activation in the right dorsal amygdala that is di- rectly related to individual real-time emotional experience. Moreover, this fear-evoked amygdala revealed two opposing networks of co-activation and co-deactivation, which correspond to vigilance and rest-related circuits, respectively. Key words: fMRI; functional cliques; individual data-driven clustering; individually tailored-based GLM function; real-time emotional rating; right dorsal amygdala Introduction O ne of the greatest challenges involved in studying the brain mechanisms of emotions is capturing the indi- vidual’s unique instantaneous experience. The acknowledge- ment of this problem goes back to Wundt’s early work asserting that no one could observe an experience better than the person having the experience (Schultz, 1975). Since then, self-reporting has been established as the leading method in experimental psychology for measuring instanta- neous emotional experiences. (Robinson and Clore, 2002). However, when the rating is in real time, it might interfere with the actual experience (Gottman and Levenson, 1985). On the other hand, when the rating is retrospective, it is sub- jected to memory and perceptual biases (Russell, 1991; Rus- sell and Barrett, 1999; Barrett et al., 2004). Thus, although the more authentic report of fear is the here-and-now ac- knowledgment of ‘‘I’m scared,’’ one should be aware that the measurement itself may affect its biological representa- tions (Rosenberg and Ekman, 1994). Nevertheless, support for the online report comes from a recent study (Mauss et al., 2005) in which behavioral (e.g., rating of facial emo- tional expressions) and physiological (e.g., heart rate, skin conductance) responses were measured during viewing of a sad movie, and the continuous ratings did not interfere with the expected affective autonomic responses. Several imaging studies aimed at determining whether real-time emotional rating would affect limbic/paralimbic neural activation. For example, (Hariri et al., 2000) showed that when processing emotional faces, the act of labeling the 1 Functional Brain Center, Wohl Institute for Advanced Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. 2 Department of Psychology, Tel Aviv University, Tel Aviv, Israel. 3 School of Computer Science, Tel Aviv University, Tel Aviv, Israel. 4 Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. BRAIN CONNECTIVITY Volume 00, Number 0, 2012 ª Mary Ann Liebert, Inc. DOI: 10.1089/brain.2011.0061 1