Figure 3.

Correlation of average local white matter volumes with cortical thickness. At each point on the surface of the brain, the average value of the local white matter volumes in the region of frontal and parietal hypoplasia for each person was correlated with the thickness of the cortical mantle at that point. Highly significant positive correlations were found in the posterior aspect of the right hemisphere, in the region of cortical thinning in our major depressive disorder (MDD) endophenotype. These correlations were found in both the high-and low-risk groups, indicating that they are independent of risk status. The correlations suggest that these regions of frontal white matter and posterior lateral cortex of the right hemisphere constitute a neural circuit. Reduced volumes in both the cortical and white matter portions of that circuit in our MDD endophenotype suggest that this biomarker affects an entire neural circuit or set of circuits within the brain.