Manganese-enhanced MRI visualizes V1 in the non-human primate visual cortex

MRI at 7 Tesla has been used to investigate the accumulation of manganese in the occipital cortex of common marmoset monkeys (Callithrix jacchus) after administering four fractionated injections of 30 mg/kg MnCl2 center dot 4H(2)O in the tail vein. We found a statistically significant decrease in T-1 in the primary (V1) and secondary (V2) areas of the visual cortex caused by an accumulation of manganese. The larger T, shortening in V1 (Delta T-1, = 640 ms) relative to V2 (AT, = 490 ms) allowed us to robustly detect the V1/V2 border in vivo using heavily T-1-weighted MRI. Furthermore, the dorso-medial (DM) and middle-temporal (MT) areas of the visual pathway could be identified by their T-1-weighted enhancement. We showed by comparison to histological sections stained for cytochrome oxidase (CO) activity that the extent of V1 is accurately identified throughout the visual cortex by manganese-enhanced MRI (MEMRI). This provides a means of visualizing functional cortical regions in vivo and could be used in longitudinal studies of phenomena such as cortical plasticity, and for non-destructive localization of cortical regions to guide in the implementation of functional techniques. Published in 2009 by John Wiley & Sons, Ltd.