Abstract
Manganese-enhanced MRI (MEMRI) has been described as a powerful tool to depict the architecture of neuronal circuits. In this study we investigated the potential use of in vivo MRI detection of manganese for tracing neuronal projections from the primary motor cortex (M1) in healthy marmosets (Callithrix Jacchus). We determined the optimal dose of manganese chloride (MnCl2) among 800, 400, 40 and 8nmol that led to manganese-induced hyperintensity furthest from the injection site, as specific to the corticospinal tract as possible, and that would not induce motor deficit. A commonly available 3T human clinical MRI scanner and human knee coil were used to follow hyperintensity in the corticospinal tract 24h after injection. A statistical parametric map of seven marmosets injected with the chosen dose, 8 nmol, showed the corticospinal tract and M1 connectivity with the basal ganglia, substantia nigra and thalamus. Safety was determined for the lowest dose that did not induce dexterity and grip strength deficit, and no behavioral effects could be seen in marmosets who received multiple injections of manganese one month apart. In conclusion, our study shows for the first time in marmosets, a reliable and reproducible way to perform longitudinal ME-MRI experiments to observe the integrity of the marmoset corticospinal tract on a clinical 3T MRI scanner.
Highlights
The corticospinal tract (CST) or pyramidal tract is the motor output from the brain to the spinal cord
The first aim of the study was to assess the feasibility of manganeseenhanced magnetic resonance imaging (ME-MRI) injected in the brain primary motor cortex (M1) marmoset in a clinical MRI scanner fitted with a human knee coil
The images were performed on a 3T Achieva (Phillips) MRI scanner equipped with standard human knee coil
Summary
The corticospinal tract (CST) or pyramidal tract is the motor output from the brain to the spinal cord. The CST is involved in two major components of motricity: strength and dexterity [1]. Nerve fibers in the corticospinal tract originate from pyramidal cells in layer V of the primary motor cortex (about 30%), the supplementary motor area and the premotor cortex (together about 30%), and the somatosensory cortex, parietal lobe, and cingulate gyrus. The CST is frequently affected in stroke and its integrity has been correlated to PLOS ONE | DOI:10.1371/journal.pone.0138308. Corticospinal Tract of the Marmoset Using Manganese-Enhanced MRI The CST is frequently affected in stroke and its integrity has been correlated to PLOS ONE | DOI:10.1371/journal.pone.0138308 September 23, 2015
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