Mean connectivity values with age.

<p>Mean connectivity values per participant are plotted by age and were significantly correlated for the <b>a.</b> left and <b>b.</b> right amygdala (left: <i>r</i> = –0.43, <i>p</i> = 1.41x10^-8; right: <i>r</i> = –0.50, <i>p</i> = 1.59x10^-11). Dashed lines indicate 95% confidence intervals.</p

Probabilistic tracts of amygdala connectivity for two example subjects.

<p>Probability maps are thresholded at 0.1 of maximum connection probability for each subject and overlaid on the same subject’s low-b diffusion image. These depict all possible tracts that the tractography algorithm used to connect the left and right amygdalae with all other target regions (i.e. the rest of the brain). Top images are the sagittal sections showing the slice locations for the coronal sections below for the adult subject (left column) and child subject (right column). Coronal slices progress posterior to anteriorly through each subject’s brain. Each slice corresponds to a similar anatomical location in both subjects but the match is not perfect due to differences in head orientation and anatomy. The adult and child subject show the same major pathways that are reconstructed by the tractography algorithm. However, the example child’s map illustrates more widespread connections than the adult participant’s map; e.g. to parietal and temporal regions; see 4^th and 5^th row from the bottom.</p

Correlations of age with mean connectivity for the four amygdala subregions.

<p>A probabilistic atlas of four amygdala subregions (illustrated in the center; coronal slice) was used to extract mean connectivity values from each subregion bilaterally per subject and plotted by age. While connectivity with the basal, lateral, and central subregions were significantly correlated with age, connectivity with the medial amygdala showed no significant change with age.</p

Amygdala volume across age.

<p>Amygdala volume is plotted by age. Volume does not correlate with age in either the <b>a.</b> left or <b>b.</b> right amygdala (left: <i>r</i> = 0.13, <i>p</i> = 0.11; right: <i>r</i> = –0.02 <i>p</i> = 0.80).</p

Magnitude of developmental changes.

<p>Magnitude of developmental changes.</p

Changes in connectivity with age.

<p>The weight, or contribution, of each target region in the final model of age by amygdala connectivity, are displayed. Negative weights represent decreasing connectivity with age, and range from dark-blue (corresponding to lower absolute weights in the model) to light-blue (higher absolute weights). Positive weights (increasing connectivity with age) are illustrated by the red- (low weights) to-yellow (high weights) colors. Right and left amygdalae are depicted in purple.</p

Mean number of ipsilateral target regions that the amygdala connects with in children and adults.

<p>Each amygdala voxel’s connectivity vector to all other target regions is thresholded at 0.1, binarized, and averaged across the amygdala per individual. In children, the amygdala showed connectivity (above 0.1) to a greater number of target regions on average than adults in both left (C: 5.57±0.18, A: 4.50± 0.16) and right (C: 5.81± 0.18, A: 4.48±0.13).</p