PMID- 19183971
OWN - NLM
STAT- MEDLINE
DCOM- 20090408
LR  - 20211020
IS  - 1432-1106 (Electronic)
IS  - 0014-4819 (Linking)
VI  - 193
IP  - 3
DP  - 2009 Mar
TI  - Suppression of EMG activity by subthreshold paired-pulse transcranial magnetic 
      stimulation to the leg motor cortex.
PG  - 477-82
LID - 10.1007/s00221-009-1704-x [doi]
AB  - Cortical activity driving a voluntary muscle contraction is inhibited by very 
      low-intensity transcranial magnetic stimulation (TMS) and is reflected in the 
      suppression of the average rectified EMG. This approach offers a method to test 
      the contribution of cortical neurons actively involved in a motor task, but 
      requires a large number of stimuli (approximately 100) to suitably depress the 
      average EMG. Here, we investigated whether two pulses of subthreshold TMS at 
      interstimulus intervals (ISIs) ranging between 1 and 12 ms could enhance the 
      amount of EMG suppression in the tibialis anterior muscle compared to a single 
      pulse. Pairs of subthreshold TMS at an ISI of 7 ms produced the maximum EMG 
      suppression that was 42% more than the inhibition elicited using a single pulse. 
      In addition, the signal-to-noise ratio of the TMS-induced suppression was further 
      increased by a second pulse, delivered 7 ms later. The reduction in the EMG at 
      the 7 ms paired-pulse interval occurred without any short-latency excitation 
      suggesting that the two stimuli increased the activation of cortical inhibitory 
      neurons. Subthreshold paired-pulse TMS at ISIs of 1-3 ms was prone to EMG 
      excitation in the period that immediately preceded the inhibition and is 
      consistent with the recruitment of short-interval intracortical facilitation 
      (SICF). We propose that pairs of subthreshold TMS outside the range of SICF with 
      an inter-pulse interval of 7 ms is optimal to inhibit ongoing cortical activity 
      during human motor movement.
FAU - Roy, Francois D
AU  - Roy FD
AD  - Department of Biomedical Engineering and Centre for Neuroscience, 513 Heritage 
      Medical Research Centre, University of Alberta, Edmonton, AB, Canada. 
      francois.roy@ualberta.ca
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20090130
PL  - Germany
TA  - Exp Brain Res
JT  - Experimental brain research
JID - 0043312
SB  - IM
MH  - Adult
MH  - Analysis of Variance
MH  - Electromyography
MH  - Female
MH  - Humans
MH  - Leg/*physiology
MH  - Male
MH  - Motor Cortex/*physiology
MH  - Muscle, Skeletal/innervation/*physiology
MH  - *Neural Inhibition
MH  - Transcranial Magnetic Stimulation
MH  - Young Adult
EDAT- 2009/02/03 09:00
MHDA- 2009/04/09 09:00
CRDT- 2009/02/03 09:00
PHST- 2008/09/20 00:00 [received]
PHST- 2009/01/08 00:00 [accepted]
PHST- 2009/02/03 09:00 [entrez]
PHST- 2009/02/03 09:00 [pubmed]
PHST- 2009/04/09 09:00 [medline]
AID - 10.1007/s00221-009-1704-x [doi]
PST - ppublish
SO  - Exp Brain Res. 2009 Mar;193(3):477-82. doi: 10.1007/s00221-009-1704-x. Epub 2009 
      Jan 30.