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Abstract #1261

An Improved Activity-Induced Manganese-Dependent MRI Study of the Rat Barrel Cortex

Nathalie Just1, Mario Lepore1, Hanne Frenkel1, Rolf Gruetter2, 3

1CIBM-AIT, EPFL, Lausanne, Switzerland; 2CIBM-AIT, cole Polytechnique Fdrale de Lausanne, Lausanne, Switzerland; 3Department of Radiology, Universities of Lausanne and Geneva, Lausanne and Geneva, Switzerland

Activity-induced Manganese dependent Magnetic Resonance Imaging (AIM-MRI) enables an indirect measurement of neuronal activity following functional challenge. However, difficulties arising from the toxicity of Mn2+ ions and their ability to cross the blood brain barrier prevent a good reproducibility. As a result, AIM MRI has not shown its full value. We increased the physiological follow up of 6 rats by carefully monitoring blood pressure during MnCl2 and mannitol infusions. T1 mapping demonstrated a significant decrease of T1 in the barrel cortex following trigeminal nerve stimulation. Finally, histogram analysis allowed an optimized characterization of the synaptic activity of the barrel cortex.