In this study from Chicago, researchers compared the responses of children to negative words. As a group, children diagnosed with bipolar affective disorder had more activation in their emotional limbic areas, and less activation in prefrontal (executive function, cognitive control) areas.
Responses to positive emotional words were exaggerated in dorsolateral prefrontal cortex, an area known to be important for attention, working memory, and response inhibition.
Feeling vs. Thinking in Pediatric Bipolar Disease