Electromyographic bursting following the cortical silent period induced by transcranial magnetic stimulation.
Brain Res
; 1446: 40-5, 2012 Mar 29.
Article
en En
| MEDLINE
| ID: mdl-22330727
In subjects performing voluntary background contraction, transcranial magnetic stimulation (TMS) induces an interruption of electromyographic (EMG) activity known as the silent period (SP). This is thought to be mediated through the action of inhibitory cortical neurons, in particular involving γ-aminobutyric acid type B (GABA(B)) receptors. In some studies of the SP, a post-SP increase in EMG activity has been reported but not described in detail. In the present study we have sought to determine the presence and persistence of late EMG bursting associated with the return of voluntary drive after the SP, and to characterize the relationship to background contraction level, stimulus intensity, and SP duration. TMS was delivered at 3 levels of intensity (120, 140 and 160% of active motor threshold) and during 3 levels of voluntary contraction of the first dorsal interosseous muscle (10, 30 and 50% of maximum contraction) in a pseudo-randomized order in 11 healthy participants. The SP was followed by a brief (~60 ms) burst of EMG up to 290±42% of the pre-stimulus EMG level. Both SP duration and the amplitude of the EMG burst increased with TMS intensity (p<0.001). Burst amplitude correlated with SP duration (r2=0.750; p=0.003). We conclude that post-SP EMG bursting is a quantifiable phenomenon that depends on the strength of TMS and the duration of the SP. This bursting may correspond with the post inhibitory period of disinhibition that has recently been identified in human motor cortex.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Depresión de Propagación Cortical
/
Potenciales Evocados Motores
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Estimulación Magnética Transcraneal
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Corteza Motora
Tipo de estudio:
Clinical_trials
Límite:
Adult
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Female
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Humans
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Male
Idioma:
En
Revista:
Brain Res
Año:
2012
Tipo del documento:
Article
País de afiliación:
Australia
Pais de publicación:
Países Bajos