Reproducibility of callosal effects of transcranial magnetic stimulation (TMS) with interhemispheric paired pulses.
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.
De Gennaro
Luigi
L
Dipartimento di Psicologia-Sezione di Neuroscienze, Università degli Studi di Roma La Sapienza, Via dei Marsi, 78, Italy. luigi.degennaro@uniroma1.it
Ferrara
Michele
M
Bertini
Mario
M
Pauri
Flavia
F
Cristiani
Riccardo
R
Curcio
Giuseppe
G
Romei
Vincenzo
V
Fratello
Fabiana
F
Rossini
Paolo Maria
PM
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