Interhemispheric differences of hand muscle representation in human motor cortex

Paola Cicinelli, Raimondo Traversa, Andrea Bassi, Giorgio Scivoletto, Paolo Maria Rossini

Research output: Contribution to journalArticlepeer-review


Focal magnetic transcranial stimulation (TCS) is employed for mapping of the motor cortical output to abductor digiti minimi (ADM) muscle. The aim of this study was to evaluate the interhemispheric asymmetries in normals. Motor maps were obtained through motor evoked potentials (MEPs) recordings from ADM muscle in 20 healthy subjects in right and left hemispheres TCS. Measurement of several indexes such as excitability threshold, MEPs amplitude, MEPs latency, and silent period duration did not show differences between the hemispheres. Moreover, no interhemispheric asymmetries were found when the amplitude ratio values were analyzed. The hand motor cortical area, as represented by the number of responsive sites (3.6 vs. 3.5) and the 'hot spot' site localization presented a fairly symmetrical organization. Absolute values displayed a relatively wide intersubject variability, while their interhemispheric differences were extremely restricted. This observation can offer a new tool in diagnosing and following up neurological disorders affecting the central motor system, mainly for those concerning monohemispheric lesions.

Original languageEnglish
Pages (from-to)535-542
Number of pages8
JournalMuscle and Nerve
Issue number5
Publication statusPublished - 1997


  • focal transcranial magnetic stimulation
  • human motor cortex
  • interhemispheric asymmetries
  • motor mapping

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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