Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/9643
Citations | ||
Scopus | Web of Science® | Altmetric |
---|---|---|
?
|
?
|
Type: | Journal article |
Title: | Responses of single motor units in human masseter to transcranial magnetic stimulation of either hemisphere |
Author: | Pearce, S. Miles, T. Thompson, P. Nordstrom, M. |
Citation: | The Journal of Physiology, 2003; 549(2):583-596 |
Publisher: | Cambridge Univ Press |
Issue Date: | 2003 |
ISSN: | 0022-3751 1469-7793 |
Statement of Responsibility: | Sophie L. Pearce, Timothy S. Miles, Philip D. Thompson and Michael A. Nordstrom |
Abstract: | The corticobulbar inputs to single masseter motoneurons from the contra- and ipsilateral motor cortex were examined using focal transcranial magnetic stimulation (TMS) with a figure-of-eight stimulating coil. Fine-wire electrodes were inserted into the masseter muscle of six subjects, and the responses of 30 motor units were examined. All were tested with contralateral TMS, and 87 % showed a short-latency excitation in the peristimulus time histogram at 7.0 ± 0.3 ms. The response was a single peak of 1.5 ± 0.2 ms duration, consistent with monosynaptic excitation via a single D- or I1-wave volley elicited by the stimulus. Increased TMS intensity produced a higher response probability (n = 13, paired t test, P< 0.05) but did not affect response latency. Of the remaining motor units tested with contralateral TMS, 7 % did not respond at intensities tested, and 7 % had reduced firing probability without any preceding excitation. Sixteen of these motor units were also tested with ipsilateral TMS and four (25 %) showed short-latency excitation at 6.7 ± 0.6 ms, with a duration of 1.5 ± 0.3 ms. Latency and duration of excitatory peaks for these four motor units did not differ significantly with ipsilateral vs. contralateral TMS (paired t tests, P> 0.05). Of the motor units tested with ipsilateral TMS, 56 % responded with a reduced firing probability without a preceding excitation, and 19 % did not respond. These data suggest that masseter motoneurons receive monosynaptic input from the motor cortex that is asymmetrical from each hemisphere, with most low threshold motoneurons receiving short-latency excitatory input from the contralateral hemisphere only. |
Keywords: | Masseter Muscle Motor Cortex Motor Neurons Humans Probability Electric Stimulation Differential Threshold Dominance, Cerebral Reaction Time Electrophysiology Adult Female Male Transcranial Magnetic Stimulation |
Description: | Copyright © 2003 The Physiological Society The definitive version is available at www.blackwell-synergy.com |
DOI: | 10.1113/jphysiol.2002.035352 |
Published version: | http://jp.physoc.org/cgi/content/abstract/549/2/583 |
Appears in Collections: | Aurora harvest Medicine publications Molecular and Biomedical Science publications |
Files in This Item:
There are no files associated with this item.
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.