PMID- 16790603
OWN - NLM
STAT- MEDLINE
DCOM- 20061102
LR  - 20220129
IS  - 0022-3077 (Print)
IS  - 0022-3077 (Linking)
VI  - 96
IP  - 4
DP  - 2006 Oct
TI  - Reduction of intracortical inhibition in soleus muscle during postural activity.
PG  - 1711-7
AB  - Short-interval intracortical inhibition (SICI) decreases during voluntary 
      contraction of the target muscle. It is unknown whether this effect also occurs 
      with postural contractions. We have compared the effects of voluntary and 
      postural contractions on SICI in the soleus (SOL) muscle. We applied transcranial 
      magnetic stimuli (TMS) in subjects under three tasks: sitting at rest (Rest), 
      sitting while activating the SOL muscle (Voluntary), or standing quietly 
      (Postural). In control trials, we applied suprathreshold TMS to obtain 
      unconditioned motor-evoked potentials (MEPs). In test trials, the same TMS was 
      preceded by a subthreshold TMS at different interstimulus intervals (ISIs), to 
      obtain a conditioned MEP. SICI and intracortical facilitation (ICF) were 
      expressed as the decrease or increase in MEP size relative to unconditioned MEPs. 
      There was significant effect of task in mean SICI or mean ICF in SOL. Mean SICI 
      in SOL was 52% in Rest and decreased to 21% in Voluntary and 15% in Postural. 
      Mean ICF in SOL was 132% and decreased to 113% in Voluntary and to 108% in 
      Postural. Mean SICI in SOL was not different in Voluntary and Postural tasks. 
      There was no effect of task in mean SICI or mean ICF in TA. Our results indicate 
      that decrease of SICI with muscle contraction occurs to a similar extent with 
      tonic voluntary and postural activation, suggesting that those contractions 
      require a similar type of cortical involvement. However, it cannot be excluded 
      that some part of the SICI reduction with muscle contraction depends on changes 
      in segmental excitability.
FAU - Soto, Oscar
AU  - Soto O
AD  - Neurology Service, Teknon Medical Center, Barcelona, Spain.
FAU - Valls-Sole, Josep
AU  - Valls-Sole J
FAU - Shanahan, Paul
AU  - Shanahan P
FAU - Rothwell, John
AU  - Rothwell J
LA  - eng
GR  - G0500258/MRC_/Medical Research Council/United Kingdom
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20060621
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
SB  - IM
MH  - Adult
MH  - Evoked Potentials, Motor/physiology
MH  - Humans
MH  - Middle Aged
MH  - Motor Cortex/*physiology
MH  - Muscle Contraction/physiology
MH  - Muscle, Skeletal/innervation/*physiology
MH  - Neural Inhibition/*physiology
MH  - Posture/*physiology
MH  - Rest/physiology
MH  - Transcranial Magnetic Stimulation
EDAT- 2006/06/23 09:00
MHDA- 2006/11/03 09:00
CRDT- 2006/06/23 09:00
PHST- 2006/06/23 09:00 [pubmed]
PHST- 2006/11/03 09:00 [medline]
PHST- 2006/06/23 09:00 [entrez]
AID - 00133.2006 [pii]
AID - 10.1152/jn.00133.2006 [doi]
PST - ppublish
SO  - J Neurophysiol. 2006 Oct;96(4):1711-7. doi: 10.1152/jn.00133.2006. Epub 2006 Jun 
      21.