Short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and short-interval intracortical facilitation (SICF) were assessed in the cortical motor area of the first dorsal interosseous muscle (FDI) of 16 healthy subjects. Paired-pulse TMS was delivered to the left hemisphere at the following interstimulus intervals (ISIs): 2 and 3 ms for SICI, 10 and 15 ms for ICF and 1–5 ms for SICF. Motor-evoked potentials were recorded from the resting and active right FDI. The effects exerted on SICI and ICF by four intensities (60–90% of active motor threshold, AMT) of the conditioning stimulus (S1) and by three levels of muscle contraction (10%, 25%, 50% of maximal voluntary contraction, MVC) were evaluated. The effects exerted on SICF were evaluatedwith two intensities (90% and 70% ofAMT) of the test stimulus (S2) and with the same levels ofmuscle contraction. Results showed that: (i) during 10%MVC, maximum SICI was observed with S1=70% AMT; (ii) the amount of SICI obtained with S1=70% AMT was the same at rest as during 10%MVC, but decreased at higher contraction levels; (iii) ICF was observed only at rest with S1=90% AMT; (iv) SICF was facilitated at 10% and 25% MVC, but not at 50% MVC. We conclude that during muscle activation, intracortical excitability reflects a balance between activation of SICI and SICF systems. Part of the reduction in SICI during contraction is due to superimposed recruitment of SICF. Lowintensity (70%AMT) conditioning

Effects of volitional contraction on intracortical inhibition and facilitation in the human motor cortex / Ortu, E; Deriu, Franca; Suppa, A; Tolu, Eusebio; Rothwell, Jc. - In: THE JOURNAL OF PHYSIOLOGY. - ISSN 0022-3751. - 586:1(2008), pp. 5147-5159. [10.1113/jphysiol.2008.158956]

Effects of volitional contraction on intracortical inhibition and facilitation in the human motor cortex

DERIU, Franca;TOLU, Eusebio;
2008-01-01

Abstract

Short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and short-interval intracortical facilitation (SICF) were assessed in the cortical motor area of the first dorsal interosseous muscle (FDI) of 16 healthy subjects. Paired-pulse TMS was delivered to the left hemisphere at the following interstimulus intervals (ISIs): 2 and 3 ms for SICI, 10 and 15 ms for ICF and 1–5 ms for SICF. Motor-evoked potentials were recorded from the resting and active right FDI. The effects exerted on SICI and ICF by four intensities (60–90% of active motor threshold, AMT) of the conditioning stimulus (S1) and by three levels of muscle contraction (10%, 25%, 50% of maximal voluntary contraction, MVC) were evaluated. The effects exerted on SICF were evaluatedwith two intensities (90% and 70% ofAMT) of the test stimulus (S2) and with the same levels ofmuscle contraction. Results showed that: (i) during 10%MVC, maximum SICI was observed with S1=70% AMT; (ii) the amount of SICI obtained with S1=70% AMT was the same at rest as during 10%MVC, but decreased at higher contraction levels; (iii) ICF was observed only at rest with S1=90% AMT; (iv) SICF was facilitated at 10% and 25% MVC, but not at 50% MVC. We conclude that during muscle activation, intracortical excitability reflects a balance between activation of SICI and SICF systems. Part of the reduction in SICI during contraction is due to superimposed recruitment of SICF. Lowintensity (70%AMT) conditioning
2008
Effects of volitional contraction on intracortical inhibition and facilitation in the human motor cortex / Ortu, E; Deriu, Franca; Suppa, A; Tolu, Eusebio; Rothwell, Jc. - In: THE JOURNAL OF PHYSIOLOGY. - ISSN 0022-3751. - 586:1(2008), pp. 5147-5159. [10.1113/jphysiol.2008.158956]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/79332
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