PMID- 11685404
OWN - NLM
STAT- MEDLINE
DCOM- 20011218
LR  - 20191210
IS  - 0014-4819 (Print)
IS  - 0014-4819 (Linking)
VI  - 140
IP  - 4
DP  - 2001 Oct
TI  - Suppression of the motor cortex by magnetic stimulation of the cerebellum.
PG  - 505-10
AB  - Conditioning magnetic stimulation of the cerebellum suppresses the motor cortex 
      5-8 ms later, probably through activation of cerebellar Purkinje cells, which 
      inhibit the dentatothalamocortical pathway. To further characterize this pathway, 
      we examined several factors that may modulate its excitability. We tested the 
      effects of different test motor evoked potential (MEP) amplitudes, voluntary 
      activation of the target muscle, and arm extension that required activation of 
      proximal arm muscles while maintaining relaxation of hand muscles. Surface 
      electromyography was recorded from the right first dorsal interosseous (FDI) 
      muscle. A double-cone coil centered 3 cm lateral to the inion was used for right 
      cerebellar stimulation. The stimulus intensity was set at 5% below the threshold 
      for activation of the corticospinal tract. A figure-of-eight coil was used for 
      left motor cortex stimulation. Interstimulus intervals (ISIs) between 3 and 15 ms 
      were studied. Small test MEPs of about 0.5 mV were markedly inhibited at ISIs of 
      5-8 ms, but there was much less inhibition for test MEPs of about 2 mV. There was 
      no significant MEP suppression during voluntary activation of the FDI muscle or 
      during right arm extension. Left arm extension did not affect inhibition. Our 
      findings indicate that cerebellar stimulation has a much stronger effect on motor 
      cortex neurons activated near threshold intensities than those activated at 
      higher intensities. Activation of contralateral but not ipsilateral proximal arm 
      muscles during arm extension reduced the excitability of the 
      cerebellothalamocortical projections to the hand area of the motor cortex.
FAU - Pinto, A D
AU  - Pinto AD
AD  - Division of Neurology, Toronto Western Hospital and Toronto Western Research 
      Institute, University Health Network, University of Toronto, Toronto, Ontario, 
      Canada.
FAU - Chen, R
AU  - Chen R
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Germany
TA  - Exp Brain Res
JT  - Experimental brain research
JID - 0043312
SB  - IM
MH  - Adult
MH  - Aged
MH  - Cerebellum/*physiology
MH  - Conditioning, Psychological/physiology
MH  - Electric Stimulation
MH  - Electromyography
MH  - Evoked Potentials, Motor/*physiology
MH  - Female
MH  - Humans
MH  - *Magnetics
MH  - Male
MH  - Middle Aged
MH  - Motor Cortex/*physiology
MH  - Movement/*physiology
MH  - Muscle Contraction/physiology
MH  - Muscle, Skeletal/physiology
MH  - Neural Inhibition/*physiology
MH  - Neural Pathways/*physiology
MH  - Neurons/*physiology
MH  - Pyramidal Tracts/physiology
MH  - Reaction Time/physiology
EDAT- 2001/10/31 10:00
MHDA- 2002/01/05 10:01
CRDT- 2001/10/31 10:00
PHST- 2001/04/18 00:00 [received]
PHST- 2001/06/26 00:00 [accepted]
PHST- 2001/10/31 10:00 [pubmed]
PHST- 2002/01/05 10:01 [medline]
PHST- 2001/10/31 10:00 [entrez]
AID - 10.1007/s002210100862 [doi]
PST - ppublish
SO  - Exp Brain Res. 2001 Oct;140(4):505-10. doi: 10.1007/s002210100862.