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Conduction pathways of motor evoked potentials following transcranial magnetic stimulation: A rodent study using a “Figure‐8” coil
Author(s) -
Kamida Tohru,
Fujiki Minoru,
Hori Shigeaki,
Isono Mitsuo
Publication year - 1998
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199806)21:6<722::aid-mus3>3.0.co;2-9
Subject(s) - lateral funiculus , transcranial magnetic stimulation , spinal cord , anatomy , stimulation , motor function , neuroscience , electrophysiology , chemistry , medicine , psychology , physical medicine and rehabilitation
We have examined the conduction pathways of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation, and their correlation with locomotor function in rats. MEPs were concomitantly recorded from the spinal cord (sMEPs) and the limb muscles (mMEPs) before and after various spinal tract ablations. Motor function was also examined using an inclined plane test. sMEPs were composed of four negative peaks (N1–N4) and mMEPs of high‐voltage, biphasic waves. Ventral funiculus transection reduced the N1–N3 peaks and abolished mMEPs. Contrarily, dorsal funiculus transection including the pyramidal tract did not alter these MEPs. Motor performance on an inclined plane was worse after ventral funiculus transection than after other transections. These findings indicate that, in rats, the N1–N3 peaks of magnetic sMEPs conduct ventral funiculus activity, and that magnetic mMEPs mainly reflect extrapyramidal activities and are correlated with locomotor function. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:722–731, 1998.