I didn't talk about that during my presentation to make sure I would be within the 10 minutes.
What you see there, the yellow and the red spots are hot spots in the brain, areas of the brain that are more active in one condition, for example, during sleep as compared to wakefulness. Those are areas of the brain that are hyperactive when people are sleeping or when they are awake, and whether they are in dream sleep or whether they are in what is supposed to be deep restorative sleep.
The slides that you see here, and these are active duty service members and veterans who were combat exposed during operations either in Iraq or Afghanistan, show that, consistently during wakefulness, as we know, pretty much all of the brain is red hot or yellow hot. It's actually localized to regions and circuits that are involved in threat response, goal-oriented behaviours, and motor preparedness. They're on the lookout, basically. They're ready to react.
What we see during sleep, during dream sleep, is that the brain doesn't change that much. They're still hyper-vigilant, ready to react to any kind of threat while they're sleeping, while they're dreaming. We do know from subsequent studies that a lot of these patterns are actually very tightly related to having nightmares.
The other slides are also looking at the same things. Red or yellow means more active brain regions. When we looked at people in deep sleep, with and without post-traumatic stress disorder, we asked the question, which regions of the brain are more active in deep sleep, which is supposed to be the restorative sleep, than in wakefulness. In those with post- traumatic stress disorder, again, you see consistently those brain networks that are involved in threat response, goal-oriented behaviours, motor preparedness, and hyper-vigilance being hyperactive.
What was surprising in the study was we found that even those who do not meet the diagnostic criteria for, or have very little symptoms of post-traumatic stress disorder, show the same kind of activation pattern during sleep as those who have PTSD. In other words, those who don't have PTSD but were deployed many times, on average three or four times for people in these studies, have this hyperactive brain; they're ready to react, ready to detect threats very quickly in the stage of sleep that is supposed to be restorative. We think this means there is an impact of chronic stress exposure on the brain that has not completely gone away even two or three years after people are back.