PMID- 18787036
OWN - NLM
STAT- MEDLINE
DCOM- 20090316
LR  - 20211020
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Print)
IS  - 0022-3751 (Linking)
VI  - 586
IP  - 21
DP  - 2008 Nov 1
TI  - Effects of volitional contraction on intracortical inhibition and facilitation in 
      the human motor cortex.
PG  - 5147-59
LID - 10.1113/jphysiol.2008.158956 [doi]
AB  - 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 evaluated with two 
      intensities (90% and 70% of AMT) of the test stimulus (S2) and with the same 
      levels of muscle 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. Low intensity (70% AMT) 
      conditioning stimuli can test SICI independently of effects on SICF at low 
      contraction levels.
FAU - Ortu, Enzo
AU  - Ortu E
AD  - Sobell Department of Motor Neuroscience and Movement Disorders, Institute of 
      Neurology, University College London, London, UK.
FAU - Deriu, Franca
AU  - Deriu F
FAU - Suppa, Antonio
AU  - Suppa A
FAU - Tolu, Eusebio
AU  - Tolu E
FAU - Rothwell, John C
AU  - Rothwell JC
LA  - eng
GR  - Medical Research Council/United Kingdom
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20080911
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
SB  - IM
MH  - Adult
MH  - Electric Stimulation/methods
MH  - Electromyography
MH  - Evoked Potentials, Motor/*physiology
MH  - Female
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Motor Cortex/*physiology
MH  - Muscle Contraction/physiology
MH  - Neural Inhibition/*physiology
PMC - PMC2652145
EDAT- 2008/09/13 09:00
MHDA- 2009/03/17 09:00
PMCR- 2009/11/01
CRDT- 2008/09/13 09:00
PHST- 2008/09/13 09:00 [pubmed]
PHST- 2009/03/17 09:00 [medline]
PHST- 2008/09/13 09:00 [entrez]
PHST- 2009/11/01 00:00 [pmc-release]
AID - jphysiol.2008.158956 [pii]
AID - 10.1113/jphysiol.2008.158956 [doi]
PST - ppublish
SO  - J Physiol. 2008 Nov 1;586(21):5147-59. doi: 10.1113/jphysiol.2008.158956. Epub 
      2008 Sep 11.