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Logo of jphysiolThe Journal of Physiology SiteMembershipSubmissionJ Physiol
J Physiol. Jun 1, 1994; 477(Pt 2): 223–235.
PMCID: PMC1155624

Suppression of voluntary motor activity revealed using transcranial magnetic stimulation of the motor cortex in man.


1. Suppression of voluntary muscle activity of hand and arm muscles in response to transcranial magnetic stimulation (TMS) of the motor cortex has been investigated in man. 2. Suppression could be elicited by low levels of TMS without any prior excitatory response. The latency of the suppression was 3-8 ms longer than the excitation observed at a higher stimulus intensity. The duration of the suppression ranged from 8 to 26 ms. 3. A circular stimulating coil was used to determine threshold intensity for excitation and suppression of contraction of thenar muscles in response to TMS at different locations over the motor cortex. The locations for lowest threshold excitation coincided with those for lowest threshold suppression. Suppression was elicited at a lower threshold than excitation at all locations. 4. A figure-of-eight stimulating coil was positioned over the left motor cortex at the lowest threshold point for excitation of the right thenar muscles. The orientation for the lowest threshold excitatory and inhibitory responses was the same for all subjects. That orientation induced a stimulating current travelling in an antero-medial direction. Suppression was invariably elicited at lower thresholds than excitation. 5. When antagonistic muscles (second and third dorsal interosseus) were co-contracted, TMS evoked coincident suppression of voluntary EMG in the two muscles without prior excitation of either muscle. This suggests that the suppression is not mediated via corticospinal activation of spinal interneurones. 6. Test responses to electrical stimulation of the cervical spinal cord were evoked in both relaxed and activated thenar muscles. In the relaxed muscle, prior TMS at an intensity that would suppress voluntary activity failed to influence the test responses, suggesting absence of inhibition at a spinal level. However, in the activated muscle, prior TMS could reduce the test response. This may be explained by disfacilitation of motoneurones due to inhibition of corticospinal output. 7. We propose that suppression of voluntary muscle activity by TMS is due in large part to activation of a mechanism within the motor cortex that reduces the corticospinal output to the muscle. It is concluded that TMS evokes excitation and inhibition via neuronal structures lying close to one another and having similar orientations.

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  • Amassian VE, Quirk GJ, Stewart M. A comparison of corticospinal activation by magnetic coil and electrical stimulation of monkey motor cortex. Electroencephalogr Clin Neurophysiol. 1990 Sep-Oct;77(5):390–401. [PubMed]
  • Amassian VE, Stewart M, Quirk GJ, Rosenthal JL. Physiological basis of motor effects of a transient stimulus to cerebral cortex. Neurosurgery. 1987 Jan;20(1):74–93. [PubMed]
  • Barker AT, Jalinous R, Freeston IL. Non-invasive magnetic stimulation of human motor cortex. Lancet. 1985 May 11;1(8437):1106–1107. [PubMed]
  • Berardelli A, Day BL, Marsden CD, Rothwell JC. Evidence favouring presynaptic inhibition between antagonist muscle afferents in the human forearm. J Physiol. 1987 Oct;391:71–83. [PMC free article] [PubMed]
  • Boniface SJ, Mills KR. Suppression of motor neuron firing by transcranial magnetic stimulation in a patient with multiple sclerosis. J Neurol Neurosurg Psychiatry. 1992 Aug;55(8):738–739. [PMC free article] [PubMed]
  • Calancie B, Nordin M, Wallin U, Hagbarth KE. Motor-unit responses in human wrist flexor and extensor muscles to transcranial cortical stimuli. J Neurophysiol. 1987 Nov;58(5):1168–1185. [PubMed]
  • Cantello R, Gianelli M, Civardi C, Mutani R. Magnetic brain stimulation: the silent period after the motor evoked potential. Neurology. 1992 Oct;42(10):1951–1959. [PubMed]
  • Cheney PD, Fetz EE, Palmer SS. Patterns of facilitation and suppression of antagonist forelimb muscles from motor cortex sites in the awake monkey. J Neurophysiol. 1985 Mar;53(3):805–820. [PubMed]
  • Datta AK, Stephens JA. The stimulus locked interval histogram: a method that may allow investigation of Renshaw inhibition in man [proceedings]. J Physiol. 1979 Aug;293:16P–17P. [PubMed]
  • Day BL, Dressler D, Maertens de Noordhout A, Marsden CD, Nakashima K, Rothwell JC, Thompson PD. Electric and magnetic stimulation of human motor cortex: surface EMG and single motor unit responses. J Physiol. 1989 May;412:449–473. [PMC free article] [PubMed]
  • Day BL, Marsden CD, Obeso JA, Rothwell JC. Reciprocal inhibition between the muscles of the human forearm. J Physiol. 1984 Apr;349:519–534. [PMC free article] [PubMed]
  • Day BL, Rothwell JC, Thompson PD, Maertens de Noordhout A, Nakashima K, Shannon K, Marsden CD. Delay in the execution of voluntary movement by electrical or magnetic brain stimulation in intact man. Evidence for the storage of motor programs in the brain. Brain. 1989 Jun;112(Pt 3):649–663. [PubMed]
  • Edgley SA, Eyre JA, Lemon RN, Miller S. Excitation of the corticospinal tract by electromagnetic and electrical stimulation of the scalp in the macaque monkey. J Physiol. 1990 Jun;425:301–320. [PMC free article] [PubMed]
  • Eisen A, Bohlega S, Bloch M, Hayden M. Silent periods, long-latency reflexes and cortical MEPs in Huntington's disease and at-risk relatives. Electroencephalogr Clin Neurophysiol. 1989 Nov-Dec;74(6):444–449. [PubMed]
  • Ellaway PH, Davey NJ, Maskill DW. Inhibition of motor unit discharge in humans evoked by transcranial magnetic stimulation. J Neurol Neurosurg Psychiatry. 1993 Jul;56(7):833–834. [PMC free article] [PubMed]
  • Ferbert A, Priori A, Rothwell JC, Day BL, Colebatch JG, Marsden CD. Interhemispheric inhibition of the human motor cortex. J Physiol. 1992;453:525–546. [PMC free article] [PubMed]
  • Fuhr P, Agostino R, Hallett M. Spinal motor neuron excitability during the silent period after cortical stimulation. Electroencephalogr Clin Neurophysiol. 1991 Aug;81(4):257–262. [PubMed]
  • Haug BA, Schönle PW, Knobloch C, Köhne M. Silent period measurement revives as a valuable diagnostic tool with transcranial magnetic stimulation. Electroencephalogr Clin Neurophysiol. 1992 Apr;85(2):158–160. [PubMed]
  • Hicks R, Burke D, Stephen J, Woodforth I, Crawford M. Corticospinal volleys evoked by electrical stimulation of human motor cortex after withdrawal of volatile anaesthetics. J Physiol. 1992 Oct;456:393–404. [PMC free article] [PubMed]
  • Illert M, Wietelmann D. Distribution of recurrent inhibition in the cat forelimb. Prog Brain Res. 1989;80:273–271. [PubMed]
  • Jankowska E, Padel Y, Tanaka R. Disynaptic inhibition of spinal motoneurones from the motor cortex in the monkey. J Physiol. 1976 Jun;258(2):467–487. [PMC free article] [PubMed]
  • Katz R, Penicaud A, Rossi A. Reciprocal Ia inhibition between elbow flexors and extensors in the human. J Physiol. 1991 Jun;437:269–286. [PMC free article] [PubMed]
  • Maccabee PJ, Amassian VE, Eberle LP, Cracco RQ. Magnetic coil stimulation of straight and bent amphibian and mammalian peripheral nerve in vitro: locus of excitation. J Physiol. 1993 Jan;460:201–219. [PMC free article] [PubMed]
  • Maertens de Noordhout A, Pepin JL, Gerard P, Delwaide PJ. Facilitation of responses to motor cortex stimulation: effects of isometric voluntary contraction. Ann Neurol. 1992 Sep;32(3):365–370. [PubMed]
  • Merton PA, Morton HB. Stimulation of the cerebral cortex in the intact human subject. Nature. 1980 May 22;285(5762):227–227. [PubMed]
  • Mills KR, Boniface SJ, Schubert M. Magnetic brain stimulation with a double coil: the importance of coil orientation. Electroencephalogr Clin Neurophysiol. 1992 Feb;85(1):17–21. [PubMed]
  • Mills KR, Murray NM. Electrical stimulation over the human vertebral column: which neural elements are excited? Electroencephalogr Clin Neurophysiol. 1986 Jun;63(6):582–589. [PubMed]
  • Palmer E, Ashby P. Corticospinal projections to upper limb motoneurones in humans. J Physiol. 1992 Mar;448:397–412. [PMC free article] [PubMed]
  • Ranck JB., Jr Which elements are excited in electrical stimulation of mammalian central nervous system: a review. Brain Res. 1975 Nov 21;98(3):417–440. [PubMed]
  • Reutens DC, Berkovic SF. Increased cortical excitability in generalised epilepsy demonstrated with transcranial magnetic stimulation. Lancet. 1992 Feb 8;339(8789):362–363. [PubMed]
  • Rothwell JC, Day BL, Thompson PD, Marsden CD. Interruption of motor programmes by electrical or magnetic brain stimulation in man. Prog Brain Res. 1989;80:467–466. [PubMed]
  • Rothwell JC, Thompson PD, Day BL, Boyd S, Marsden CD. Stimulation of the human motor cortex through the scalp. Exp Physiol. 1991 Mar;76(2):159–200. [PubMed]
  • Wassermann EM, Fuhr P, Cohen LG, Hallett M. Effects of transcranial magnetic stimulation on ipsilateral muscles. Neurology. 1991 Nov;41(11):1795–1799. [PubMed]
  • Widmer CG, Lund JP. Evidence that peaks in EMG averages can sometimes be caused by inhibition of motoneurons. J Neurophysiol. 1989 Jul;62(1):212–219. [PubMed]

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