Fig. 1. Sagittal section through left amygdala showing position and orientation of 18 acquired coronal oblique slices.

Fig. 2. Two-mm thick coronal sections from y = −1 to y = −11 depicting mean SNR, with Talairach atlas amygdala ROI outlined. The color scale ranges from an SNR of 50 (yellow) to an SNR of 100 (red).

Fig. 3. Histogram of mean voxel SNR values for left and right Talairach-based amygdala ROIs.

Fig. 4. Statistically defined clusters in left and right amygdala, based upon fear–baseline contrast for scan session 1. This and all other brain images are presented in radiological format (i.e., left of image = right of brain). Images thresholded at P < 0.01 corrected for multiple comparisons. Coronal sections are 2 mm thick and extend from y = 0 to y = −10 (clusters were confined to areas of activation that fell within the amygdala as defined by the Talairach atlas).

Fig. 5. Plots of statistical power versus number of subjects, given two levels of contrast variability and three hypothesized contrast effect sizes.

Fig. 6. Scatterplots of fear versus neutral, fear versus baseline and neutral versus baseline for the statistically defined left amygdala cluster. Left column: scatterplots for 0 versus 2 weeks; right column: scatterplots for 0 versus 8 weeks. All values represent percent signal change.

Fig. 7. Statistical maps of fear–baseline (left) and neutral–baseline (right) contrasts for the 3 scan sessions, for the amygdala region as indicated by the rectangle in the whole coronal slice (top). Coronal sections are 2 mm thick and extend from y = 0 to y = −10. Images thresholded at P < 0.01 uncorrected for multiple comparisons. A liberal threshold has been used in these images to permit a comparison of activation across sessions, including activation that would fall just under threshold in a more stringent, corrected statistical test.

Mean reported anxiety across the scan sessions

Numbers in parentheses are standard deviations.

Contrast indices extracted from Talairach and statistically defined ROIs

Numbers in parentheses are standard deviations.

Intraclass correlation coefficients for the whole, Talairach-defined amygdala

Intraclass correlations for the amygdala cluster defined on the basis of fear activation in the first session

Single measure ICCs for the left amygdala statistical ROI for 4 mm blurred and non-blurred percent signal change and z score data