Stimulation of the dorsolateral prefrontal cortex modulates muscle sympathetic nerve activity and blood pressure in humans

Figures

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  Fig. 1. Multi-unit recording of MSNA, together with the RMS-processed neurogram (RMS nerve), ECG, heart rate (HR), blood pressure (BP), and respiration at rest and during tcACS over the ipsilateral dlPFC. Discriminated, negative-going (sympathetic) spikes extracted from the nerve recording are illustrated as standard pulses (spikes). The times of occurrence of each heartbeat (R-waves) and the positive peaks of the sinusoidal dlPFC stimulation at 0.08 Hz are also shown as standard pulses (stimuli). The selection in the right panel, obtained 4 min into the stimulation, emphasizes the cyclic fluctuations in BP and heart rate, and clustering of MSNA, during tcACS over the ipsilateral dlPFC.

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  Fig. 2. A, C) Cross-correlation histogram between MSNA and stimulation over the right dlPFC (ipsilateral) at 0.08 Hz in 2 participants. The continuous line shows the smoothed polynomial (counts/bin indicated on right axis). Three cycles of the sinusoidal stimulus are superimposed to illustrate the timing of the stimulation. B, D) Corresponding cross-correlation histograms between MSNA and ECG (gray bars), with the autocorrelogram of the R-waves shown in black (right axis). Five cardiac cycles are shown. Note that the timescales of the upper and lower panels are different. In all panels time 0 represents the reference event for the cross-correlation histograms (sinusoidal stimulus or R-wave) or auto-correlation histograms (R-wave).

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  Fig. 3. A, C) Cross-correlation histogram between MSNA and stimulation between the right C4 (hand area) electrode and Cz (vertex) at 0.08 Hz in 2 participants. The continuous line shows the smoothed polynomial (counts/bin indicated on right axis). Three cycles of the sinusoidal stimulus are superimposed to illustrate the timing of the stimulation. B, D) Corresponding cross-correlation histograms between MSNA and ECG (gray bars), with the autocorrelogram of the R-waves shown in black (right axis). Five cardiac cycles are shown. Note that the timescales of the upper and lower panels are different. In all panels time 0 represents the reference event for the cross-correlation histograms (sinusoidal stimulus or R-wave) or auto-correlation histograms (R-wave).

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  Fig. 4. Cross-correlation histograms between MSNA and dlPFC stimulation at 0.08 Hz over the right (ipsilateral) and left (contralateral) dlPFC in 2 participants. The continuous line shows the smoothed polynomial (counts/bin indicated on right axis). Three cycles of the sinusoidal stimulus are superimposed to illustrate the timing of the stimulation.

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  Fig. 5. Modulation indices computed for stimulation of the left (n = 10) and right (n = 22) dlPFC. Central horizontal line represents the median, surrounding box represents the interquartile range.

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  Fig. 6. Cross-correlation histograms between systolic BP (black bars) or diastolic BP (gray bars) and the R-waves in 4 participants A–D) during sinusoidal stimulation of the right dlPFC. The positive phase of the sinusoidal stimulation cycle is superimposed to illustrate the timing of the stimulation. Data are not available for −6 s in C) because this participant had a very low heart rate.

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  Fig. 7. Modulation Indices (mean ± SD) for systolic and diastolic BP as well as heart rate across all 100 cycles of dlPFC stimulation (n = 21). P < 0.0001 for all variables, derived by one-sample t-tests.

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  Fig. 8. Maximal fluctuations in mean BP at baseline and during stimulation of the right dlPFC. Median ± interquartile range (n = 21).