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Modulation of human corticomotor excitability by somatosensory input

Authors
 Alain Kaelin Lang  ;  Andreas R. Luft  ;  Lumy Sawaki  ;  Aaron H. Burstein  ;  Young H. Sohn  ;  Leonardo G. Cohen 
Citation
 JOURNAL OF PHYSIOLOGY-LONDON, Vol.540(2) : 623-633, 2002 
Journal Title
JOURNAL OF PHYSIOLOGY-LONDON
ISSN
 0022-3751 
Issue Date
2002
MeSH
Adolescent ; Adult ; Brain Stem/drug effects ; Brain Stem/physiology ; Dextromethorphan/pharmacology ; Electric Stimulation ; Electromagnetic Fields ; Electrophysiology ; Evoked Potentials, Motor/drug effects ; Evoked Potentials, Motor/physiology ; Evoked Potentials,Somatosensory/drug effects ; Evoked Potentials,Somatosensory/physiology ; Female ; GABA Modulators/pharmacology ; Hand/innervation ; Hand/physiology ; Humans ; Lorazepam/pharmacology ; Magnetoencephalography ; Male ; Middle Aged ; Motor Cortex/drug effects ; Motor Cortex/physiology* ; Motor Neurons/drug effects ; Motor Neurons/physiology ; Recruitment, Neurophysiological/drug effects ; Recruitment, Neurophysiological/physiology ; SomatosensoryCortex/drug effects ; SomatosensoryCortex/physiology* ; gamma-Aminobutyric Acid/physiology
Abstract
In humans, somatosensory stimulation results in increased corticomotoneuronal excitability to the stimulated body parts. The purpose of this study was to investigate the underlying mechanisms. We recorded motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) from abductor pollicis brevis (APB), first dorsal interosseous (FDI), and abductor digiti minimi (ADM) muscles. MEP amplitudes, recruitment curves (RC), intracortical inhibition (ICI), intracortical facilitation (ICF), resting (rMT) and active motor thresholds (aMT) were recorded before and after a 2-h period of ulnar nerve electrical stimulation at the wrist. Somatosensory input was monitored by recording somatosensory evoked potentials. To differentiate excitability changes at cortical vs. subcortical sites, we recorded supramaximal peripheral M-responses and MEPs to brainstem electrical stimulation (BES). In order to investigate the involvement of GABAergic mechanisms, we studied the influence of lorazepam (LZ) (a GABAA receptor agonist) relative to that of dextromethorphan (DM) (an NMDA receptor antagonist) and placebo in a double-blind design. We found that somatosensory stimulation increased MEP amplitudes to TMS only in the ADM, confirming a previous report. This effect was blocked by LZ but not by either DM or placebo and lasted between 8 and 20 min in the absence of (i) changes in MEPs elicited by BES, (ii) amplitudes of early somatosensory-evoked potentials or (iii) M-responses. We conclude that somatosensory stimulation elicited a focal increase in corticomotoneuronal excitability that outlasts the stimulation period and probably occurs at cortical sites. The antagonistic effect of LZ supports the hypothesis of GABAergic involvement as an operating mechanism.
Files in This Item:
T200208168.pdf Download
DOI
10.1113/jphysiol.2001.012801
Appears in Collections:
1. College of Medicine (의과대학) > Dept. of Neurology (신경과학교실) > 1. Journal Papers
Yonsei Authors
Sohn, Young Ho(손영호) ORCID logo https://orcid.org/0000-0001-6533-2610
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/144223
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