Figure 1.

Coronal MRI sections showing the habenula and the local anatomical landmarks that enabled its segmentation. Because the habenular nuclei contain relatively dense white matter plexuses they can be delimited from the gray matter of the adjacent thalamus dorsolaterally, and by the limitans nucleus and pretectal area ventrolaterally [23]. Moreover, in posterior planes the habenula is clearly evident as a pyramidal-shaped structure that bulges into the third ventricle along the ventromedial aspect of the thalamus, whereas in anterior planes it can be delimited ventrally and medially from the thalamus by the stria medullaris of thalamus (the white matter track that delimits the ventromedial aspect of the medial thalamus). In the image shown the habenular location shows sufficient asymmetry that the typical view of the posterior aspect is illustrated by the habenular nuclear complex located on the reader's left, while the latter case is illustrated by the habenular complex on the reader's right. Finally, the habenular nuclei are delimited ventrally by the white matter of the posterior commissure. The medial and lateral habenular nuclei could not be resolved specifically, so were combined within a single habenular volume-of-interest. The upper and lower panels are identical images. The tracing of the habenula is shown in yellow in the lower panel.