In vivo detection of neuroarchitecture in the rodent brain using manganese-enhanced MRI

Aoki, Ichio, et al. "In vivo detection of neuroarchitecture in the rodent brain using manganese-enhanced MRI." Neuroimage 22.3 (2004): 1046-1059. Manganese-enhanced magnetic resonance imaging has been developed for multiple uses over the past couple decades including functional MRI and neuronal tract tracing. In this paper Aoki's laboratory examined how MeMRI could be used to visualize cytoarchitecture in the brain in order to further understand brain structures. Several brain regions in particular were reviewed including the olfactory bulb, cortex, ventricles, hippocampus, brainstem, and cerebellum. Manganese chloride was given intravenously at a rate of 1.8 ml/hr with a final concentration of 884.3 micromols/kg. Rats were broken into four groups and imaged at time points 0-2hrs, 1 day, 4 days, and 14 days post manganese chloride administration. After the analysis, most brain regions of interest had peak signal intensity 24 hours post injection such as the hippocampus, coritcal areas, subcortical areas, cerebellum, and the brainstem. However some brain regions closely associated with the ventricles showed peak manganese accumulation after only 2 hours. These brain regions include the ventricles themselves, the pituitary, pineal gland, and the medium eminence. More importantly, this paper was one of the first to distinguish between different sub-layers of certain brain regions. For example three separate molecular cell layers were distinguishable within the cerebellum. The same goes for the olfactory bulb where six distinguished layers were found with the MRI signal. These findings are important for future longitudinal studies focusing on architecture under different conditions such as development or drug abuse. ~JI