The hippocampus is the region of the brain associated with learning and memory.  Interestingly, the hippocampus not only helps us remember the past, it also is integral to making sense of our future narrative.  Those who have had their hippocampus removed not only don’t remember the past, but cannot project a narrative for their future.  The hippocampus also processes the rise of stress hormones.  It also plays the role of telling the hypothalamus to stop producing the stress response.  It itself is sensitive to the effects of stress.  The hippocampus interacts with the amygdala to remember emotionally significant things, so also plays an important part in our emotional responses.  Chronic stress has been shown to shrink the hippocampus as well as its response in helping stop the cycle of stress.