Neural correlates of delicate sadness: an fMRI study based on the neuroaesthetics of Noh masks Naoyuki Osaka a , Takehiro Minamoto a , Ken Yaoi a and Mariko Osaka b Although the role of the amygdala in processing facial expressions of fear is well established, its role in the processing of other emotions, such as sadness, remains unclear. We hypothesized that the amygdala would respond to a negative emotion such as sadness, when sadness was represented by a theatrical mask. In the traditional Japanese Noh theater, performers use masks to indicate many of the mental states of the characters they portray. Here, we report a functional MRI study, in which participants’ brains were scanned while viewing Noh masks, whose faces appeared delicately sad. Among seventy standard Noh masks previously rated by the individual participants, we chose six top-rated sad masks and six neutral masks to study the neural correlates of such delicate sadness. Results based on a region of interest analysis indicated the activation of the right amygdala while viewing sad masks. We suggest the fact that such delicate sad masks could activate the amygdala, and it could possibly be because of an underlying similarity to emotions such as fear and disgust. NeuroReport 23:26–29  c 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins. NeuroReport 2012, 23:26–29 Keywords: emotion, facial expression, functional MRI, Noh mask, sadness a Department of Psychology, Graduate School of Letters, Kyoto University, Kyoto and b Department of Psychology, Graduate School of Human Sciences, Osaka University, Osaka, Japan Correspondence to Dr Naoyuki Osaka, PhD, Department of Psychology, Graduate School of Letters, Kyoto University, Kyoto 606-8501, Japan Tel/fax: + 81 75 753 2796; e-mail: nosaka@bun.kyoto-u.ac.jp Received 2 October 2011 accepted 4 October 2011 Introduction Sadness likely plays a critical role in stage performances such as Noh, a traditional Japanese theater style, in which the main performers put on symbolic masks representing their major emotions (such as sadness) in an elegant manner. However, the neural correlates of elegant sadness experienced by viewers when such masks are used are not well understood. The universals of facial expression are to be found in the relationship between distinctive patterns of facial muscles and six basic emotions, such as sadness, happiness, anger, disgust, fear, and surprise [1]. Thus, sadness is a primary negative emotion representing one particular human mental feeling state [2–5]. Among these basic emotions, negative emotions such as fear have been shown to activate the amygdala: the so-called ‘emotion center’ of the human limbic brain [6]. Recent investigation suggests that the amygdala is not merely a ‘fear center’ in the brain, but also works as an ‘emotional center’ involving both negative and positive emotions. However, not everyone agrees that the amygdala could also affect positive emotions such as happiness. For example, Osaka and Minamoto [7] reported that a happiness mask could activate the striatal area involving the nucleus accumbens (Nacc), but would not activate the amygdala. Few studies have examined whether sadness, like fear, shares similar neural correlates with the amygdala. If sadness shares such correlates, then we could interpret sadness, fear, and disgust as three aspects of a shared emotional system. Methodologically, it is unknown whether a face mask is a kind of stimulus that could effectively elicit sadness in a viewer. We decided to investigate whether this could be accomplished using a Noh mask that is elegant and artistically polished, and designed to express sadness. We report a functional MRI (fMRI) study, in which participants were scanned while watching Noh masks, whose faces appeared delicately sad. In the present study, we hypothesized that, in contrast to a happy face, a sad face could serve as an effective stimu- lus to trigger sadness. As a consequence, we assumed the amygdala, instead of the Nacc, would probably be activated. Why use a Noh mask instead of a face picture or cartoon in such an experiment? The Noh mask covers a wide range of complex emotions (including the major six emotions) in a somewhat symbolic manner. For example, several types of masks, in particular those for females, are designed so that slight adjustments in the position of the head can express a number of emotions (such as sadness and happiness) as a function of variations in lighting and the angle displayed to the audience. This suggests that, some Noh masks could be used as emotionally ambiguous faces [8] suitable for the use as neutral (control) condition in an fMRI experiment. Methods Participants Fourteen healthy, right-handed participants (seven men and seven women; mean age = 25.2) were recruited in 26 Cognitive neuroscience and neuropsychology 0959-4965  c 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI: 10.1097/WNR.0b013e32834dccda Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.