High-definition transcranial direct-current stimulation of the right M1 further facilitates left M1 excitability during crossed facilitation

V, Cabibel; M, Muthalib; WP, Teo; S, Perrey

Abstract:

The crossed-facilitation (CF) effect refers to when motor-evoked potentials (MEPs) evoked in the relaxed muscles of one arm are facilitated by contraction of the opposite arm. The aim of this study was to determine whether high-definition transcranial direct-current stimulation (HD-tDCS) applied to the right primary motor cortex (M1) controlling the left contracting arm [50% maximum voluntary isometric contraction (MVIC)] would further facilitate CF toward the relaxed right arm. Seventeen healthy right-handed subjects participated in an anodal and cathodal or sham HD-tDCS session of the right M1 (2 mA for 20 min) separated by at least 48 h. Single-pulse transcranial magnetic stimulation (TMS) was used to elicit MEPs and cortical silent periods (CSPs) from the left M1 at baseline and 10 min into and after right M1 HD-tDCS. At baseline, compared with resting, CF (i.e., right arm resting, left arm 50% MVIC) increased left M1 MEP amplitudes (+97%) and decreased CSPs (−11%). The main novel finding was that right M1 HD-tDCS further increased left M1 excitability (+28.3%) and inhibition (+21%) from baseline levels during CF of the left M1, with no difference between anodal and cathodal HD-tDCS sessions. No modulation of CSP or MEP was observed during sham HD-tDCS sessions. Our findings suggest that CF of the left M1 combined with right M1 anodal or cathodal HD-tDCS further facilitated interhemispheric interactions during CF from the right M1 (contracting left arm) toward the left M1 (relaxed right arm), with effects on both excitatory and inhibitory processing.

Patologie/Applicazioni:

• Stimolazione elettrica transcranica (TES)

Anno:

2018

Tipo di pubblicazione:

Articolo

Parola chiave:

stimolazione elettrica transcranica; hd-tdcs

Nota:

Il lavoro si propone di verificare se la HD-tDCS può modificare l'effetto di facilitazione incrociata di un arto sull'omologo controlaterale (crossed facilitation-CF) durante l'esecuzione dei Potenziali Evocati Motori. I risultati dello studio, eseguito con stimolazione attiva e sham, suggeriscono che l'erogazione di HD-tDCS anodica e catodica favorisce le interazioni corticali inter-emisferiche con effetti sia eccitatori che inibitori.

DOI:

10.1152/jn.00861.2017