title: Manganese-enhanced MRI visualizes V1 in the non-human primate visual cortex.
abstract: 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 MnCl(2) . 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(1) shortening in V1 (DeltaT(1) = 640 ms) relative to V2 (DeltaT(1) = 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.
authors.affiliation: Cerebral Microcirculation Unit, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1065, USA. bockn@mail.nih.gov
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Bock
authors.forename: Ara
authors.initials: A
authors.lastname: Kocharyan
authors.forename: Afonso C
authors.initials: AC
authors.lastname: Silva