In vivo visualization and analysis of primate retinal projection pathway using manganese-enhanced MRI tract-tracing. Presidential award proceedings

Manganese-enhanced magnetic resonance imaging (MEMRI) tract-tracing has been used for in situ morphological analysis of several experimental animals, including rodents. We used a 7-tesla MR imager to perform this seminal technique on common marmoset monkeys, whose complex retinal projection pathway is analogous to the human visual pathway. We found that the distribution of divalent manganese cation (Mn2+) extricated from MnCl2 solution injected into unilateral eyes produced marked contrast enhancement that clearly delineated the retinal projection pathway. Configurations of the retinal innervations depicted by MEMRI tract-tracing were consistent with findings of previous histopathological studies. In conclusion, MEMRI tract-tracing is a robust tool for in vivo neuronal imaging analysis of the non-human primate visual pathway as well as for other experimental medical research in animals. (author)