“The brain is a system of highly interacting parts, and we need methods that allow us to study it as such.”

I think there are two main reasons. The first is that it addresses a topic—the neurobiology of emotionally influenced memory—widely viewed as very important for the field. The second is that we have employed a type of analysis that those involved with human brain imaging increasingly realize they need, namely, a method that allows investigators to go beyond simply identifying which areas "light up," to assessing how the different brain areas influence each other. The brain is a system of highly interactive parts, and we need methods that allow us to study it as such. Who tells who what to do, and when? This is what we are trying to discover. We used a method called "path analysis" to determine how influences from a key brain region called the "amydgala" cause other brain regions to change in emotional as compared with neutral learning situations.

As I mentioned above, it described a method that is not technically new, but is now starting to be widely applied in human brain imaging. Many investigators realize they have to "go there" and develop these methods in their own work, which can be hard to do. Our paper likely helps many see a bit more clearly as to how it can be done.

We try to understand how the brain stores memory, in particular for emotional events. A theory, very well supported by animal research, holds that a structure called the amygdala is critical to the enhancing effect of emotion on memory. According to this theory, the amygdala modulates—or amplifies—memory storage occurring in other brain regions when an experience is emotionally arousing. Our results provided the first direct evidence for this theory in the human brain.

For over 25 years, I have been interested in how the brain stores memory. Emotional arousal seems to be one of the most important determinants of whether and how well memory is stored. So, it was natural for me to begin studying emotion’s influence on memory. I began with animal studies, which led to testing predictions based on this work in humans. That in turn led me into human brain imaging studies such as this.