PMID- 8930851
OWN - NLM
STAT- MEDLINE
DCOM- 19970310
LR  - 20220321
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 496 ( Pt 3)
IP  - Pt 3
DP  - 1996 Nov 1
TI  - Interaction between intracortical inhibition and facilitation in human motor 
      cortex.
PG  - 873-81
AB  - 1. In seven normal subjects, subthreshold transcranial magnetic conditioning 
      stimuli (using a figure-of-eight coil) were applied over the motor cortex in 
      order to evoke activity in intracortical neuronal circuits. The net effect on 
      cortical excitability was evaluated by measuring the effect on the size of EMG 
      responses elicited in the abductor digiti minimi (ADM) muscle by a subsequent 
      suprathreshold test stimulus. 2. A single conditioning stimulus suppressed the 
      size of the test response at interstimulus intervals (ISIs) of 1-4 ms whereas the 
      response was facilitated at ISIs of 6-20 ms. The facilitation could be augmented 
      if pairs of conditioning stimuli were given. 3. Inhibition and facilitation 
      appeared to have separate mechanisms. The threshold for inhibition (0.7 active 
      motor threshold) was slightly lower than that for facilitation (0.8 active 
      threshold). Similarly, the inhibitory effect was independent of the direction of 
      current flow induced in the cortex by the conditioning shock, whereas 
      facilitation was maximal with posterior-anterior currents and minimal with 
      lateromedial current. 4. Direct corticospinal effects were probably not 
      responsible for the results since facilitation of cortical test responses could 
      be produced by conditioning stimuli which had no effect on the amplitude of H 
      reflexes elicited in active ADM muscle. 5. Inhibition and facilitation appeared 
      to interact in a roughly linear manner, consistent with separate inputs to a 
      common neurone. 6. We suggest that subthreshold transcranial magnetic stimulation 
      is capable of activating separate populations of excitatory and inhibitory 
      interneurones in the motor cortex.
FAU - Ziemann, U
AU  - Ziemann U
AD  - MRC Human Movement and Balance Unit, Institute of Neurology, London, UK.
FAU - Rothwell, J C
AU  - Rothwell JC
FAU - Ridding, M C
AU  - Ridding MC
LA  - eng
PT  - Journal Article
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
SB  - IM
MH  - Adult
MH  - Conditioning, Psychological
MH  - Electric Stimulation
MH  - Electromyography
MH  - Fingers/innervation
MH  - Humans
MH  - Magnetics
MH  - Male
MH  - Motor Cortex/*physiology
MH  - Muscle, Skeletal/*innervation
MH  - Perception
MH  - Reaction Time
MH  - Spinal Cord/physiology
PMC - PMC1160871
EDAT- 1996/11/01 00:00
MHDA- 1996/11/01 00:01
PMCR- 1996/11/01
CRDT- 1996/11/01 00:00
PHST- 1996/11/01 00:00 [pubmed]
PHST- 1996/11/01 00:01 [medline]
PHST- 1996/11/01 00:00 [entrez]
PHST- 1996/11/01 00:00 [pmc-release]
AID - 10.1113/jphysiol.1996.sp021734 [doi]
PST - ppublish
SO  - J Physiol. 1996 Nov 1;496 ( Pt 3)(Pt 3):873-81. doi: 
      10.1113/jphysiol.1996.sp021734.