What happens in your brain when you are afraid during a scuba dive? Which brain regions are representing the very useful emotion "fear"? Fear can serve both to keep a person from doing something unduly dangerous, or it can decrease enjoyment of an activity which is actually safe, or it can escalate into panic, causing danger by itself.
How does nitrogen narcosis affect the processing of fear? There are some studies out which looked at this question. The effects are subtle. In divers who are anxious to begin with, fear interferes most with cognitive processing, for example.
For a more in-depth discussion heck out my new article for DAN on the topic please!