Figure 2.

Periventricular nodular heterotopia. The first image (A), shows an axial MRI scan from a normal individual, showing the normal configuration of the cerebral cortex, and ventricular lining. The ventricles show white matter signal right down to the ventricular surface, except for a small part of the ventricle shown on the left side where the body of the caudate nucleus appears near the ventricular surface. The middle image (B) shows an MRI scan of a woman with periventricular nodular heterotopia due to a mutation in the FLNA gene, in this case a de novo mutation not shared by her parents. The small arrows highlight the continuous lining of the ventricular surface on both sides with irregular nodules that show identical signal characteristics to normal cerebral cortex. Figure C is adapted from Christodoulou et al (2012) (with permission) and shows resting-state functional connectivity MRI with bold oxygenation level-dependent (BOLD) imaging. The periventricular nodules in this patient are highly active, and their activity is synchronized with overlying cortex, suggesting that these abnormally placed nodules are structurally and functionally integrated into cerebral cortical circuits.