Whole Brain Hemodynamic Response Based on Synchrony Analysis of Brain Signals for Effective Application of HD-tDCS in Stroke Patients: An fNIRS Study

Figures

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  Figure 1. Experimental design. (A) Experimental conditions. (B) A head cap including the tDCS electrodes and fNIRS optodes. (C) Topography for tDCS electrodes and fNIRS optodes location.

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  Figure 2. The average cortical activation maps of 26 subjects analyzed by using the NIRS-SPM software before (prerest), during, and after (post-rest) tDCS intervention.

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  Figure 3. The cortical synchrony results analyzed by using the OptoNet II® software based on the total 22 timeframes in all 26 subjects. The green circles—functional brain regions, the colored lines—the synchrony connections, the lightning mark—the tDCS target.

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  Figure 4. The mean PLV values based on the timeframe in each hemisphere and a whole brain. The error bar indicates the standard deviations between all related channels. The asterisk indicates a statistical difference compared to the pre-test value (* p < 5/100; ** p < 1/100; *** p < 1/1000), and the cross indicates a statistical difference between affected and unaffected intrahemispheric connections († p < 5/100; †† p < 1/100; ††† p < 1/1000).

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  Figure 5. The number of synchrony connections over the threshold level before (pre-test), during, and after (post-rest) tDCS intervention. (A) Inter synchrony showed number of synchrony connections between the two hemispheres. Intra synchrony showed number of synchrony connections within the unaffected hemisphere (B) and the affected hemisphere (C). The asterisk indicates a statistical difference compared to the pre-test value (* p < /1005; ** p < 1/100)).