Objective: To investigate the distribution of conduction pathways of somtosensory evoked potential (SEP) and motor evoked potential (MEP) in the spinal cord.
Methods: Twenty-five Wistar rats underwent operation to expose the left sciatic nerve and sphenotresia. The sciatic nerve and sensory-motor cortex of 10 rats were stimulated so as to induce MEP and SEP. Different stimulating parameters were used to record their influence on MEP and SEP. Then the microelectrode was removed to a new place 1 cm from the original place and the maximum MEP and maximum SEP were recorded so as to calculate the conduction speeds of MEP and SEP. A microelectrode was put to the ventral side of spinal cord of 15 rats so as to record the isopotential map of MEP and SEP in the spinal cord.
Results: The Ni-P1 of SEP increased when the microelectrode was moved from the anterior side to the posterior side and the change was more prominent in the anterior funiculus area. The N2-P2 decreased when the microelectrode was moved from anterior side to posterior side, and the change was more prominent in the posterior funiculus area.
Conclusion: SEP is mainly conducted in the posterior tracts and MEP in the anterior tracts. MEP may originate from extra-pyramid system.