Kevin C. Chan1,2, Jiang Li3, Iris
Y. Zhou1,2, Kwok-fai So3, Ed X. Wu1,2
1Laboratory of Biomedical Imaging and
Signal Processing, The University of Hong Kong, Hong Kong SAR, China; 2Department
of Electrical and Electronic Engineering, The University of Hong Kong, Hong
Kong SAR, China; 3Department of Anatomy, The University of Hong
Kong, Hong Kong SAR, China
This
study explores the capability of high-resolution 3D Mn-enhanced MRI (MEMRI)
for in vivo retinotopic mapping of the rat superior colliculus (SC) upon
partial transection of the intraorbital optic nerve. Upon intravitreal Mn2+
injection into both eyes, all animals in Group 1 (n=8) exhibited
significantly lower signal intensity in the lateral side of the left SC
compared to the left medial SC and right control SC 1 week after superior
optic nerve transection in the right eye. Partial transection at other
regions of the optic nerve in Group 2 (n=7) led to hypointensity in other
regions of the left SC. The results of this study demonstrated the
feasibility of high-resolution MEMRI for in vivo, 3D mapping of retinotopic
projections in the SC upon reduced anterograde axonal transport of Mn2+ ions
at sites of partial transections in the anterior visual pathways. Future
MEMRI studies are envisioned that measure the retinotopic changes in normal
development, disease, plasticity and therapy in longitudinal studies.