title: Reproducibility of callosal effects of transcranial magnetic stimulation (TMS) with interhemispheric paired pulses.
abstract: Transcranial magnetic stimulation (TMS) of the motor cortex of one hemisphere (conditioning stimulus (CS)) inhibits EMG responses evoked in distal hand muscles by a later magnetic stimulus given at an appropriate interval, over the opposite hemisphere (test stimulus (TS)). This effect is commonly attributed to an inhibition produced at cortical level via a transcallosal route. The present study assessed the reproducibility of the transcallosal inhibition effects in different sessions in healthy subjects. Within- and between-subject variability, relating to interhemispheric differences was also evaluated. A magnetic CS on one hemisphere effectively inhibited EMG responses of the abductor digiti minimi stimulated by a TS delivered over the opposite hemisphere in a range of intervals centered at 12 ms. Even though group effects were reproduced in separate sessions, the high between- and within-subject variability yielded low test-retest correlations. This differentiation forces the definition of reproducibility (or repeatability), as the replication of the same mean curves of EMG reduction, and of reliability, as the between- or within-subject correlations between values of specific EMG measures.
authors.affiliation: Dipartimento di Psicologia-Sezione di Neuroscienze, Università degli Studi di Roma La Sapienza, Via dei Marsi, 78, Italy. luigi.degennaro@uniroma1.it
authors.forename: Luigi
authors.initials: L
authors.lastname: De Gennaro
authors.forename: Michele
authors.initials: M
authors.lastname: Ferrara
authors.forename: Mario
authors.initials: M
authors.lastname: Bertini
authors.forename: Flavia
authors.initials: F
authors.lastname: Pauri
authors.forename: Riccardo
authors.initials: R
authors.lastname: Cristiani
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Curcio
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Romei
authors.forename: Fabiana
authors.initials: F
authors.lastname: Fratello
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D000328:Adult; D003213:Conditioning, Psychological / Q000502:physiology; D003337:Corpus Callosum / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006225:Hand / Q000294:innervation; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology*; D015203:Reproducibility of Results; D050781:Transcranial Magnetic Stimulation