Accuracy in the Recording of Motor Evoked Potentials in Rodents: Reaction Evoked by Transcranial Magnetic Stimulation and Electrical Stimulation
An understanding of the motor conduction pathway and its origin is very important in rehabilitation medicine. With the recent increase of using transcranial magnetic stimulation (TMS), the mechanisms of motor control have been analyzed more directly. Monitoring of motor evoked potentials (MEPs) following magnetic stimulation, especially those from the muscles of the extremities, is useful clinically because central and peripheral motor functions can be evaluated conveniently and noninvasively. Many studies of magnetic MEPs have been reported using monkeys and cats. Although rodents are most frequently and conveniently used for other experiments, there have been only a few reports about magnetic MEPs in rodents. I attempted to record MEP induced by magnetic or electrical stimulation in fifteen Japanese white rabbits and three Wistar rats. However, they could not be recorded in any of the animals by either magnetic stimulation or electrical stimulation using a bipolar electrode. When the electrical stimulation was performed using a monopolar electrode, definite waves of MEP were not recorded in any of the materials except for one rabbit. It is suggested that general anesthesia inhibited the appearance of MEP.