F1 shows the brain activation sites in the PTSD and comparison groups. Areas of significantly increased BOLD response across all subjects in each group are shown. The t values are represented by the color of the activation sites. The unidirectional hypotheses stated in the introduction were based on previous studies (1–6), as well as on our own pilot data. One-tailed t tests were therefore used. Regions of activation during traumatic memory recall versus implicit baseline where the comparison group (N=9) showed greater activation than the PTSD group included the right thalamus (Talairach coordinates, x=12, y=–12, z=2) (t=8.98, df=741.5, p=0.0001), left thalamus (x=–4, y=–14, z=18) (t=6.93, df=741.5, p=0.0001), left medial frontal gyrus (Brodmann’s area 10/11) (x=0, y=34, z=–12) (t=6.84, df=741.5, p=0.0001), right medial frontal gyrus (Brodmann’s area 10/11) (x=0, y=34, z=–12) (t=6.84, df=741.5, p=0.0001), left anterior cingulate gyrus (Brodmann’s area 32) (x=0, y=34, z=–12) (t=6.84, df=741.5, p=0.0001), right anterior cingulate gyrus (Brodmann’s area 32) (x=0, y=34, z=–12) (t=6.84, df=741.5, p=0.0001), and the right occipital lobe (Brodmann’s area 19) (x=28, y=–86, z=38) (t=6.06, df=741.5, p=0.0001).
Brain activation patterns during the first 30 seconds of recall were similar to those during the final 30 seconds of recall. Amygdala activation was not observed at any time during the recall of the traumatic memory. Brain activation returned to baseline during the rest periods in all brain areas studied for both the PTSD and the comparison groups. Time courses of activation showed that 60 seconds was enough time for the subjects to recover from the traumatic scripts. Baseline brain activation did not differ between the PTSD subjects and the comparison subjects (data not shown). The PTSD subjects showed a greater increase in heart rate from baseline than the comparison subjects (PTSD group: mean=12 bpm, SD=7; comparison group: mean=2 bpm, SD=2; t=4.2, df=10, p=0.0004, one-tailed).