PMID- 16760345
OWN - NLM
STAT- MEDLINE
DCOM- 20061102
LR  - 20060915
IS  - 0022-3077 (Print)
IS  - 0022-3077 (Linking)
VI  - 96
IP  - 4
DP  - 2006 Oct
TI  - Origin of facilitation of motor-evoked potentials after paired magnetic 
      stimulation: direct recording of epidural activity in conscious humans.
PG  - 1765-71
AB  - A magnetic transcranial conditioning stimulus given over the motor cortex at 
      intensities below active threshold for obtaining motor-evoked potentials (MEPs) 
      facilitates EMG responses evoked at rest in hand muscles by a suprathreshold 
      magnetic stimulus given 10-25 ms later. This is known as intracortical 
      facilitation (ICF). We recorded descending volleys produced by single and paired 
      magnetic motor cortex stimulation through high cervical epidural electrodes 
      implanted for pain relief in six conscious patients. At interstimulus intervals 
      (ISIs) of 10 and 15 ms, although MEP was facilitated, there was no change in the 
      amplitude or number of descending volleys. An additional I wave sometimes was 
      observed at 25 ms ISI. In one subject, we also evaluated the effects of reversing 
      the direction of the induced current in the brain. At 10 ms ISI, the facilitation 
      of the MEPs disappeared and was replaced by slight suppression; at 2 ms ISI, 
      there was a pronounced facilitation of epidural volleys. Subsequent experiments 
      on healthy subjects showed that a conditioning stimulus capable of producing ICF 
      of MEPs had no effect on the EMG response evoked by transmastoidal electrical 
      stimulation of corticospinal tract. We conclude that ICF occurs because either 1) 
      the conditioning stimulus has a (thus far undetected) effect on spinal cord 
      excitability that increases its response to the same amplitude test volley or 2) 
      that it can alter the composition (but not the amplitude) of the descending 
      volleys set up by the test stimulus such that a larger proportion of the activity 
      is destined for the target muscle.
FAU - Di Lazzaro, V
AU  - Di Lazzaro V
AD  - Institute of Neurology, Universita Cattolica, Rome, Italy. 
      vdilazzaro@rm.unicatt.it
FAU - Pilato, F
AU  - Pilato F
FAU - Oliviero, A
AU  - Oliviero A
FAU - Dileone, M
AU  - Dileone M
FAU - Saturno, E
AU  - Saturno E
FAU - Mazzone, P
AU  - Mazzone P
FAU - Insola, A
AU  - Insola A
FAU - Profice, P
AU  - Profice P
FAU - Ranieri, F
AU  - Ranieri F
FAU - Capone, F
AU  - Capone F
FAU - Tonali, P A
AU  - Tonali PA
FAU - Rothwell, J C
AU  - Rothwell JC
LA  - eng
PT  - Journal Article
DEP - 20060607
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
SB  - IM
MH  - Adult
MH  - Electric Stimulation
MH  - Electromyography
MH  - Evoked Potentials, Motor/*physiology
MH  - H-Reflex/physiology
MH  - Humans
MH  - Middle Aged
MH  - Motor Cortex/*physiology
MH  - Muscle, Skeletal/innervation/physiology
MH  - Pyramidal Tracts/*physiology
MH  - Reaction Time
MH  - *Transcranial Magnetic Stimulation
EDAT- 2006/06/09 09:00
MHDA- 2006/11/03 09:00
CRDT- 2006/06/09 09:00
PHST- 2006/06/09 09:00 [pubmed]
PHST- 2006/11/03 09:00 [medline]
PHST- 2006/06/09 09:00 [entrez]
AID - 00360.2006 [pii]
AID - 10.1152/jn.00360.2006 [doi]
PST - ppublish
SO  - J Neurophysiol. 2006 Oct;96(4):1765-71. doi: 10.1152/jn.00360.2006. Epub 2006 Jun 
      7.