PMID- 11251064
OWN - NLM
STAT- MEDLINE
DCOM- 20010517
LR  - 20191210
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 531
IP  - Pt 3
DP  - 2001 Mar 15
TI  - Interhemispheric facilitation of the hand motor area in humans.
PG  - 849-59
AB  - 1. We investigated interhemispheric interactions between the human hand motor 
      areas using transcranial cortical magnetic and electrical stimulation. 2. A 
      magnetic test stimulus was applied over the motor cortex contralateral to the 
      recorded muscle (test motor cortex), and an electrical or magnetic conditioning 
      stimulus was applied over the ipsilateral hemisphere (conditioning motor cortex). 
      We investigated the effects of the conditioning stimulus on responses to the test 
      stimulus. 3. Two effects were elicited at different interstimulus intervals 
      (ISIs): early facilitation (ISI = 4-5 ms) and late inhibition (ISI > or = 11 ms). 
      4. The early facilitation was evoked by a magnetic or anodal electrical 
      conditioning stimulus over the motor point in the conditioning hemisphere, which 
      suggests that the conditioning stimulus for early facilitation directly activates 
      corticospinal neurones. 5. The ISIs for early facilitation taken together with 
      the time required for activation of corticospinal neurones by I3-waves in the 
      test hemisphere are compatible with the interhemispheric conduction time through 
      the corpus callosum. Early facilitation was observed in responses to I3-waves, 
      but not in responses to D-waves nor to I1-waves. Based on these results, we 
      conclude that early facilitation is mediated through the corpus callosum. 6. If 
      the magnetic conditioning stimulus induced posteriorly directed currents, or if 
      an anodal electrical conditioning stimulus was applied over a point 2 cm anterior 
      to the motor point, then we observed late inhibition with no early facilitation. 
      7. Late inhibition was evoked in responses to both I1- and I3-waves, but was not 
      evoked in responses to D-waves. The stronger the conditioning stimulus was, the 
      greater was the amount of inhibition. These results are compatible with surround 
      inhibition at the motor cortex.
FAU - Hanajima, R
AU  - Hanajima R
AD  - Department of Neurology, Division of Neuroscience, Graduate School of Medicine, 
      University of Tokyo, Tokyo, Japan.
FAU - Ugawa, Y
AU  - Ugawa Y
FAU - Machii, K
AU  - Machii K
FAU - Mochizuki, H
AU  - Mochizuki H
FAU - Terao, Y
AU  - Terao Y
FAU - Enomoto, H
AU  - Enomoto H
FAU - Furubayashi, T
AU  - Furubayashi T
FAU - Shiio, Y
AU  - Shiio Y
FAU - Uesugi, H
AU  - Uesugi H
FAU - Kanazawa, I
AU  - Kanazawa I
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
SB  - IM
MH  - Conditioning, Psychological
MH  - Corpus Callosum/physiology
MH  - Electric Stimulation
MH  - Hand/*physiology
MH  - Humans
MH  - Magnetics
MH  - Motor Cortex/*physiology
MH  - Neural Conduction/physiology
MH  - Neural Inhibition/physiology
MH  - Time Factors
PMC - PMC2278503
EDAT- 2001/03/17 10:00
MHDA- 2001/05/18 10:01
PMCR- 2002/03/15
CRDT- 2001/03/17 10:00
PHST- 2001/03/17 10:00 [pubmed]
PHST- 2001/05/18 10:01 [medline]
PHST- 2001/03/17 10:00 [entrez]
PHST- 2002/03/15 00:00 [pmc-release]
AID - PHY_11264 [pii]
AID - 10.1111/j.1469-7793.2001.0849h.x [doi]
PST - ppublish
SO  - J Physiol. 2001 Mar 15;531(Pt 3):849-59. doi: 10.1111/j.1469-7793.2001.0849h.x.