<qa>  What is the brain circuit that is critical for the extinction of conditioned fear responses?It is well-established that the practice of mindfulness meditation leads to improvements in mental health and well-being and the cultivation of positive emotions. However, the neural mechanisms of these improvements are largely unknown. A few recent studies suggest that mindfulness meditation impacts the structure and function of the ventromedial prefrontal cortex, the hippocampus, and the amygdala. Interestingly, recent studies have shown that these regions are part of a brain circuit that is critical for the extinction of conditioned fear responses, and for the retention of fear extinction memory. Building on the overlap of these regions and on conceptual considerations, the project investigates whether mindfulness meditation could influence ones capacity to retain the memory of fear extinction. Meditation-naïve participants will be randomized to either a mindfulness-meditation based training or an active control training that controls for all mindfulness-unspecific components. Participants will undergo a fear conditioning, extinction and extinction recall protocol in an MRI scanner before and after the trainings. We hypothesize that participants who have practiced mindfulness meditation will show greater improvements in fear extinction memory after the course, and that these improvements will be correlated with anatomical and functional changes in the brain regions of interest. Improvements in fear extinction memory will also be related to improvements in self-reported psychological well-being. Merging the fields of an ancient spiritual tradition and a fundamental learning mechanism, the project investigates the underlying neural mechanisms of a practice for the enhancement of mental health and well-being. 