Refining the Sensory and Motor Ratunculus of the Rodent Upper Extremity: Evaluation of the C7 Nerve Root Using FMRI and Direct Nerve Stimulation

Patrick C. Hettinger¹, Rupeng Li², Ji-Geng Yan¹, Hani S. Matloub¹, Young R. Cho¹, Matthew L. Runquist², Christopher P. Pawela¹, James S. Hyde²

The purpose of this study is to further define the ratunculus by observing cortical activity using BOLD fMRI during direct stimulation of the C7 nerve root. In this study, 7 Sprague-Dawley rats underwent implantable electrode placement on the C7 nerve root. BOLD response to nerve stimulation was then studied using a Bruker 9.4T MRI scanner. C7 nerve stimulation resulted in a small amount of activation in the S1FL region along with a large amount of activation within the M1/M2 regions. These findings are similar to the sensory and motor distributions described in human C7 nerve root literature.