Handedness is mainly associated with an asymmetry of corticospinal excitability and not of transcallosal inhibition

Luigi De Gennaro, Riccardo Cristiani, Mario Bertini, Giuseppe Curcio, Michele Ferrara, Fabiana Fratello, Vincenzo Romei, Paolo M. Rossini

Research output: Contribution to journalArticlepeer-review

Abstract

Objective The study aims to compare transcallosal inhibition (TI), as assessed by the paired-pulse transcranial magnetic stimulation (TMS) technique, in a sample of right-handed subjects (RH) and left-handed subjects (LH). Motor thresholds (MTs) and motor evoked potential (MEP) amplitudes were also measured in the two groups, as an index of corticospinal activity. Methods Thirty-two normal subjects (16 RH and 16 LH) were recorded with a paired-pulse TMS paradigm (intensity of both pulses=120% of MT). The inter-stimulus intervals (ISIs) were 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 ms for both motor cortices, and MEP responses were recorded from the abductor digiti minimi muscles. Results Both groups showed a clear TI centred around the 12 ms ISI, but no difference was found as a function of handedness or of hemisphere. On the other hand, the two groups differed in terms of corticospinal activity, since the hand motor dominant hemisphere had lower MTs than the non-dominant one in LH, and larger MEP amplitudes for the right hand were found in RH. Conclusions Results point to a functional asymmetry of the motor cortex on the hand-dominant versus the non-dominant hemisphere, while handedness does not seem associated with functional differences in callosal inhibition, as measured by the inter-hemispheric paired-pulse TMS technique.

Original languageEnglish
Pages (from-to)1305-1312
Number of pages8
JournalClinical Neurophysiology
Volume115
Issue number6
DOIs
Publication statusPublished - Jun 2004

Keywords

  • Corpus callosum
  • Corticospinal system
  • Gender
  • Handedness
  • Paired-pulse technique
  • Transcallosal inhibition
  • Transcranial magnetic stimulation

ASJC Scopus subject areas

  • Clinical Neurology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Sensory Systems
  • Physiology (medical)

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