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. Author manuscript; available in PMC: 2023 May 10.
Published in final edited form as: Brain Stimul. 2022 Dec 24;16(1):56–67. doi: 10.1016/j.brs.2022.12.011

Fig. 2. Selection of electrode montage.

Fig. 2.

Electrode polarities under anodal stimulation are shown. (a) Electric field estimated for an individual subject with a 4+4 electrode montage (red and blue circles represent 4 anodes and 4 cathode, respectively). This montage was optimized to achieve maximum intensity at the voxel in the “hand knob” with the highest fMRI activation, with current flowing from posterior to anterior direction normal to the cortical surface under anodal stimulation. As expected, for maximal polarizing intensity, fields are broadly distributed. (b) 2D views of estimated electric field on gray matter resulting from stimulation for the same subject in (a). White arrows represent electric field vectors and red rings mark the manually selected “hand knob” target. (c) Tally of how often an electrode location (in the 10-10 system) was selected by the optimization routine in ROAST for the 10 individual subjects models and targets (red: anodes, blue: cathodes) (d) Locations selected (with the highest tally in panel c) for a common montage that was used for all subjects during the motor sequence learning task. Anodes (red) each inject 1 mA and cathodes (blue) each draw 1 mA for a total of 4 mA of constant current stimulation.