Focal Hemodynamic Responses in the Stimulated Hemisphere During High-Definition Transcranial Direct Current Stimulation

M, Muthalib; P, Besson; J, Rothwell; S, Perrey

Abstract:

OBJECTIVE: High-definition transcranial direct current stimulation (HD-tDCS) using a 4 × 1 electrode montage has been previously shown using modeling and physiological studies to constrain the electric field within the spatial extent of the electrodes. The aim of this proof-of-concept study was to determine if functional near-infrared spectroscopy (fNIRS) neuroimaging can be used to determine a hemodynamic correlate of this 4 × 1 HD-tDCS electric field on the brain. MATERIALS AND METHODS: In a three session cross-over study design, 13 healthy males received one sham (2 mA, 30 sec) and two real (HD-tDCS-1 and HD-tDCS-2, 2 mA, 10 min) anodal HD-tDCS targeting the left M1 via a 4 × 1 electrode montage (anode on C3 and 4 return electrodes 3.5 cm from anode). The two real HD-tDCS sessions afforded a within-subject replication of the findings. fNIRS was used to measure changes in brain hemodynamics (oxygenated hemoglobin integral-O2 Hbint ) during each 10 min session from two regions of interest (ROIs) in the stimulated left hemisphere that corresponded to "within" (Lin ) and "outside" (Lout ) the spatial extent of the 4 × 1 electrode montage, and two corresponding ROIs (Rin and Rout ) in the right hemisphere. RESULTS: The ANOVA showed that both real anodal HD-tDCS compared to sham induced a significantly greater O2 Hbint in the Lin than Lout ROIs of the stimulated left hemisphere; while there were no significant differences between the real and sham sessions for the right hemisphere ROIs. Intra-class correlation coefficients showed "fair-to-good" reproducibility for the left stimulated hemisphere ROIs. CONCLUSIONS: The greater O2 Hbint "within" than "outside" the spatial extent of the 4 × 1 electrode montage represents a hemodynamic correlate of the electrical field distribution, and thus provides a prospective reliable method to determine the dose of stimulation that is necessary to optimize HD-tDCS parameters in various applications.

Patologie/Applicazioni:

• Stimolazione elettrica transcranica (TES)

Anno:

2017

Tipo di pubblicazione:

Articolo

Parola chiave:

ossigenazione cerebrale; stimolazione elettrica transcranica; neuromodulazione; hd-tdcs

Testata scientifica:

Neuromodulation

Nota:

L'obiettivo di questo lavoro è valutare se la spettroscopia ad infrarossi (NIRS) può essere utilizzata come correlato emodinamico della stimolazione elettrica transcranica. I soggetti sono stati sottoposti ad HD-tDCS e alla contemporanea registrazione emodinamica con tecnologia NIRS. La variazione dell'emoglobina registrata nell'area stimolata e intorno ad essa correla con la distribuzione del campo elettrico, offrendo una prospettiva alla NIRS come metodo di dosaggio della stimolazione utile ad ottimizzare i parametri della HD-tDCS.

DOI:

10.1111/ner.12632