Elsevier

Brain Research

Volume 636, Issue 2, 14 February 1994, Pages 270-276
Brain Research

Physiological motor asymmetry in human handedness: evidence from transcranial magnetic stimulation

https://doi.org/10.1016/0006-8993(94)91026-XGet rights and content

Abstract

We hypothesized that human handedness might be associated with measurable differences in the excitability of the motor system. We compared the thresholds for electromyographic activation of the left and right abductor pollicis brevis (APB) and biceps muscles in 30 left-handers and 30 right-handers, by varying the direction of a brief monophasic pulse in a circular electromagnetic coil centered over the vertex of the scalp. In right-handers, we found that the threshold for activation of muscles in the right arm was lower than the threshold for activation of corresponding muscles in the left arm. In left-handers, the reverse was true. Threshold asymmetry was influenced significantly by the consistency with which each subject used the writing hand to perform other motor tasks, and was not significant between non-consistent left-handers and right-handers. Our results indicate that human handedness, and in particular, consistency of hand preference, are associated with lateralized differences in the excitability of motor system projections activated by transcranial magnetic stimulation. Our findings might reflect physiological differences in corticospinal tract function or cortical motor representation.

References (53)

  • WitelsonS.F.

    Neuroanatomical asymmetry in left-handers

  • AmassianV.E. et al.

    Physiological basis of motor effects of a transient stimulus to cerebral cortex

    Neurosurgery

    (1987)
  • AnnettM.

    The binomial distribution of right, mixed and left handedness

    Q.J. Exp. Psychol.

    (1967)
  • BarnsleyR.H. et al.

    Handedness: proficiency versus stated preference

    Percept. Mot. Skills

    (1970)
  • Brasil-NetoJ.P. et al.

    Postexercise depression of motor evoked potentials: a measure of central nervous system fatigue

    Exp. Brain Res.

    (1993)
  • ChiappaK.H. et al.

    Magnetic stimulation: determination of coil current flow direction

    Neurology

    (1991)
  • DattaA.K. et al.

    Task-dependent changes in the size of the response to magnetic brain stimulation in human first dorsal interosseous muscle

    J. Physiol.

    (1989)
  • DavidoffR.A.

    The pyramidal tract

    Neurology

    (1990)
  • DayB.L. et al.

    Direction of current in magnetic stimulation coils used for percutaneous activation of brain, spinal cord and peripheral nerve

    J. Physiol.

    (1990)
  • DayB.L. et al.

    Electric and magnetic stimulation of human motor cortex: surface EMG and single motor unit responses

    J. Physiol.

    (1989)
  • DayB.L. et al.

    Changes in the response to magnetic and electrical stimulation of the motor cortex following muscle stretch in man

    J. Physiol.

    (1991)
  • FennellE.B.

    Handedness in neuropsychological research

  • GeschwindN. et al.

    Cerebral lateralization. Biological mechanisms, associations, and pathology: I. A hypothesis and a program for research

    Arch. Neurol.

    (1985)
  • HeilmanK.M. et al.

    Apraxia and agraphia in a left-hander

    Brain

    (1973)
  • HeilmanK.M. et al.

    Apraxia

  • HessC.W. et al.

    Responses in small hand muscles from magnetic stimulation of the human brain

    J. Physiol.

    (1987)
  • Cited by (151)

    • The causal role of the left parietal lobe in facilitation and inhibition of return

      2019, Cortex
      Citation Excerpt :

      The session began by first determining the hotspot for the first dorsal interosseous (FDI) – defined as the optimum site over primary motor cortex (M1) which evoked the highest contralateral motor evoked potentials (MEP) in the relaxed FDI. Then, we determined the resting motor threshold (rMT), defined as the minimum stimulus intensity which elicits MEPs > 50 μV in five out of ten consecutive trials (Chen, Yung, & Li, 2003; Rossini et al., 2015; Triggs, Calvanio, Macdonell, Cros, & Chiappa, 1994). Electromyography (EMG) and MEPs were recorded from the right FDI by using snap surface electrodes (Natus Neurology).

    • Temporal Profile and Limb-specificity of Phasic Pain-Evoked Changes in Motor Excitability

      2018, Neuroscience
      Citation Excerpt :

      In this analysis, a main effect of ‘perception’, or an interaction between the factors ‘perception’ and the factors ‘ISI cluster’ or ‘side’ would indicate that nociceptive stimuli perceived as more or less intense do not exert the same effect on motor excitability. A baseline recording of MEPs was performed at the beginning and at the end of the experiment (20 TMS pulses delivered using a constant 6–7 s inter-trial interval), to assess potential inter-block cumulative effects of the repeated TMS pulses (Pellicciari et al., 2016) and/or differences related to hand dominance (Triggs et al., 1994). The average amplitude of the MEPs obtained at the two baseline measurements were compared using a two-way repeated-measures ANOVA with the factors ‘time’ (beginning vs. end of the experiment) and ‘dominance’ (MEPs recorded from the dominant vs. non-dominant limb).

    View all citing articles on Scopus
    View full text