Figure 3. | Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

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Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

Figure 3.

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City College of the City University of New York, United States; New York University School of Medicine, United States; Mayo Clinic, United States
Figure 3.
Download figureOpen in new tabFigure 3. Voltage recordings across multiple intracranial locations for sinusoidal transcranial alternating current stimulation for the first subject tested (P03).

Magnitude and sign are estimated by fitting a sinusoid to the voltage fluctuations at each electrode location. (A) Voltage recordings at multiple intracranial recording locations are linear with stimulation intensity up to 1 mA in this subject (each curve represents a different electrode). At higher intensities some channels saturate due to a limited dynamic range of the clinical recording equipment, which is demonstrated by the plateauing of measured voltage at intensities above 1.5 mA. (B) Intensities are constant with frequency in the range of 1–10 Hz. The drop-off at higher frequencies is due to the recording equipment. (C) Averaged measurements across three stimulation sessions (separated by approximately 1 min each) demonstrate stability of electric field measurements across sessions. (Here stimulation was 1 Hz and between 0.5–1 mA in stimulation current. The voltage values are calibrated to correspond to 1 mA stimulation). Error bars at each electrode indicate the variability across different stimulation blocks.

DOI: http://dx.doi.org/10.7554/eLife.18834.004