Equanimity is derived from traditional Buddhism and is defined as an even-minded mental state or dispositional tendency toward all experiences or objects, regardless of their origin or their affective valence (i.e., pleasant, unpleasant, or neutral). It has recently attracted attention in the field of psychology. Equanimity is one of the most important concepts for clarifying the neural and psychological mechanism of mindfulness and compassion meditation. This article reviews five topics: mindfulness in traditional Buddhism and in modern psychology, equanimity in Buddhism, the construct of equanimity in psychology, equanimity in the process of emotion regulation of mindfulness meditation, and the neural mechanism of emotion regulation in mindfulness meditation. Based on these reviews, this article proposes that equanimity, which decouples desire from feeling, is related to the attenuated response to prediction errors, which is associated with the anterior insular cortex and striatum. Further research investigating the neural mechanism of these relations directly is needed to clarify the neural and psychological mechanisms of mindfulness and compassion meditation.
