However, the subjects with PTSD did not activate any part of their frontal lobe, which means they could not muster any curiosity about the stranger. They just reacted with intense activation deep inside their emotional brains, in the primitive areas known as the Periaqueductal Gray, which generates startle, hypervigilance, cowering, and other self-protective behaviors. There was no activation of any part of the brain involved in social engagement. In response to being looked at they simply went into survival mode.
