Novel response patterns during repeated presentation of affective and neutral stimuli.

Repeated stimulus presentations are commonly used in social and affective neuroimaging tasks, but much remains to be known about how the brain processes such repetitions. Using functional magnetic resonance imaging, we found three groups of brain regions with distinct response patterns during repeated presentations of natural scene images. One group consisted of several limbic, paralimbic, frontoparietal and medial prefrontal areas and showed a habituation-like response across pleasant, unpleasant, and neutral image categories. A second group of occipital and adjacent posterior cortical regions showed a pattern of diminishing responses with repeated presentations of affective images but not for neutral images, and also plateaued to activation levels above baseline for all image categories. A third group involved bilateral frontopolar areas and the precuneus and exhibited a novel, non-monotonic response pattern. Activity was low on the first presentation, peaked upon the second presentation (first repetition) and subsequently diminished. These findings indicate that the transition from novel to increasingly familiar, and also arousing to less arousing, involves a broad array of neural mechanisms alluding to both passive learning and active inference strategies.