Changes in Callosal and Thalamic Connectivity Following Peripheral Nerve Damage to the Rodent Forepaw Detected with Manganese Enhanced MRI

Jason Tucciarone¹, Galit Pelled¹, Alan Koretsky¹

The purpose of this work was to determine if MEMRI neural tracing could detect changes in the laminar functional architecture of cortical-cortical and thalamo-cortical somatosensory pathways following complete nerve deafferentation of the rat forepaw. Previously it has been demonstrated that cortical reorganization observed following complete peripheral nerve injury affects functional MRI responses both in healthy and deprived cortices. Reduced manganese transport was found in lamina 3 of the deprived cortex after injection of manganese to the healthy cortex predicting that input into this layer has decreased. Second, increases in T1 enhancement in the healthy cortex were found after injecting manganese into the healthy thalamus. There was increased tracing throughout the cortex which was highest at the lamina 3/4 interface. Thus, both cortical-cortical and thalamic-cortical neuronal pathways are affected by the injury, and contribute to the deprived somatosensory reorganization.