Inappropriate SNS arousal may result in features of the current stimuli (now perceived as a threat) being remembered as having features it associates with fear and trauma. Thus, the resultant strong stimulus overgeneralization prompts increasingly powerful, inappropriate fear responses that are increasingly resistant to extinction (becoming dissociated from fear) and habituation (Armony & LeDoux; Garrick et al., 1997; McEwen & Magarinos). In turn, hippocampal failure to encode memory context (chronology and location) with emotional valence and sensory data is believed to contribute significantly to establishing and maintaining core PTSD symptoms of re-experiencing and arousal (Armony & LeDoux; Morgan et al., 1997; Roozendaal et al., 1997).

4. During trauma exposure or re-experience, language centers of the left brain (Broca’s area and left frontal cortex) tend to shut down and the right brain (particularly limbic structures) tends to be more active.

Reports of several MRI studies in which groups with and without PTSD read narrative scripts of their own or others’ traumatic events (Gerhards, Yehuda, Shoham, & Hellhammer, 1997; Pitman, 1997; Rauch & Shin, 1997; Spiegel, 1997; van der Kolk et al., 1997) suggest that during trauma exposure for those with PTSD, a shift occurs in regional cerebral blood flow (rCBF) away from left brain, in particular showing decreases in Broca’s area and the left frontal cortex, and toward greater activation of the right brain, in particular the right amygdala and right frontal pole.