Abstract

Motor evoked potentials(MEPs) have been used widely both experimentally and clinically to study the function of the motor nervous system. However, the origins and the waveforms of MEPs in small animals like rats may be different from those of potentials evoked by intracortical microstimulation in carnivore like cats because of current spread. The patterns and characteristics of MEPs also could be affected by recording techinques and methods of stimulation. In the present study, we used a specially designed electrode to stimulate localized cortical area. The pointed tip of a special stimulating electrode was inserted into the cerebral cortex perpendicular to the cortical surface so that the round area gently contacted with the cortical surface. We investigated the characteristics of pyramidal motor evoked potentials (PMEPs) and extrapyramidal motor evoked potentials (EPMEPs) evoked by the electrical stimulation of the mortex cortex and the gigantocellular reticular nucleus. Using this technique, we could constantly obtain the PMEP and EPMEP. The results of the present study showed that the PMEP and the EPMEP were different in their latencies and waveforms.