Figure 1.

Illustration of optic nerve and regions of interest in the axial and coronal MRI images of an adult rhesus monkey. (A) Mean diffusivity (MD); (B) fractional anisotropy (FA) maps (both in 0.65 mm isotropic resolution after interpolation) of the same animal; (C) Region of interest (ROI) overlaid on the MD map. The ROI was selected manually between the anterior and posterior quarters of the optic nerve (see the axial image at the top), only including the central pixels of the optic nerve cross-sections (see the coronal image at the bottom) on the selected slices; (D) The two masks for optic nerve fiber tractography were selected on the middle slice (coronal image) of the optic nerves between the optic chiasm and retina, and 2.2 mm away from the middle slice, toward the eyeball; (E) T1 weighted images (0.5 mm isotropic resolution) of the optic nerve. The optic nerves are marked with arrows on the axial image at the top and on the coronal image at the bottom.