Finally, individual group contrasts were performed to substantiate the PTSD versus controls difference. Again, these specific contrasts revealed consistent results to those from the main analyses (Table 3). A notable difference was that, owing to the reduced group size, the PCC→VC deficit in PTSD at S-RS survived one-tailed tests only (PTSD vs HC: t = −1.72, p = 0.046 one-tailed, d = 0.52; vs GAD: t = −1.83, p = 0.037 one-tailed, d = 0.53), as did the VC→PCC deficit in the double contrast (PTSD vs HC, t = −1.87, p = 0.034 one-tailed, d = 0.57; PTSD vs GAD, t = −1.87, p = 0.035 one-tailed, d = 0.55). However, given the strong a priori hypothesis of deficient α connectivity in PTSD, these tests could provide support to the hypothesis. The double contrast on VC→mPFC α connectivity showed a significant deficit in PTSD in comparison to GAD (t = −2.29, p = 0.027, d = 0.67) but only a marginal deficit in comparison to HC (t = −1.50, p = 0.071 one-tailed, d = 0.46).
