I am not a therapist by any means but my understanding of the amygdala is that it is a warning bell for fear. So if you see something that your brain does not feel is safe, it goes off and you will feel adrenaline, panic, etc... It does not necessarily mean that you are remembering what you are currently seeing as something from your past but you may be feeling body sensations you felt in the past.

There is a book called The Body Keeps the Score which explains it all. Good book.