Article Figures & Data
Figures
- Figure 1.
Electrode locations. A, Anatomical locations of recording sites across 15 patients that are closest to the cortical and medial surfaces. Each dot location indicates the sEEG depth electrode entry point through the cortex or exit point through the medial view, therefore the locations are not exact as sEEG electrodes are not necessarily directly on the surface. Dot color indicates patient ID. B, ROI anatomic map that was used to group channel pairs for analysis.
- Figure 2.
HRV calculations. A, Sample 4-s ECG signal; the RR interval is determined from the time difference between subsequent R peaks. B, Example calculations of HFnorm for two 1-min intervals, one with an overall sympathetic tone (top row) and one with an overall parasympathetic tone (bottom row). The very LF trend (magenta line) is removed from the raw RR intervals (left-most plots), resulting in the detrended time series (middle plots). PSD estimates show that most of the power is in the “HF” (0.15–0.4 Hz) for the parasympathetic interval (right-most plots). C, Calculated normalized HF power for the two intervals displayed in Figure 2B. The bar colors correspond to the matching colors in the spectral estimation plots.
- Figure 3.
Correlation of population neural activity (HGnorm) and estimated parasympathetic balance (HFnorm). The distribution of the Fisher z-transformed correlation coefficient z values for each ROI in each sleep stage is displayed in the topmost plots (A–C), The red dots are statistically significant channel pairs, whereas the blue dots are not (FDR corrected p < 0.05). The mean and 95% confidence interval of the z values are displayed in panels D–F. Regions where the mean z is significantly differ from zero are labeled with an asterisk. Each cortical region is color coded according to Figure 1B.
- Figure 4.
Correlation of population neural activity and autonomic state after conditioning on δ. Similarly to Figure 3D–F, the means and 95% confidence intervals of the z values calculated from the correlation between HGnorm and HFnorm but after conditioning on δ band activity and applying the Fisher z-transformation on the correlation coefficients. Color coding of cortical ROIs are equivalent to Figure 1B. The unconditioned mean and 95% confidence intervals shown in Figure 3D–F are superimposed in light gray to facilitate their comparison. Regions where the mean z is significantly differ from zero are labeled with an asterisk.
- Figure 5.
Distribution of responsive channels across locations and sleep stages. The percentage of channels where the correlation of HGnorm and HFnorm is statistically significant in each ROI is plotted for each sleep stage, with conditioning on δ activity (light colors) and without (dark colors). Percentage values for each ROI/sleep stage/correlation measure are shown in Extended Data Table 5-1.
- Figure 6.
Possible functional relationships underlying the correlation between cortical and hippocampal activity and HRV during sleep. Panels A–C show the possible causal relationships between cortical activity, heart rate variability, and brain stem autonomic effectors that could explain the results shown in this work.
Tables
Patient Age
(mean ± SD)Sex Handedness Number of
channelsNumber of
sleep periodsNumber of 1-min samples NREM1 NREM2 NREM3 CC04 20 M Right 20 3 141 178 175 CC08 58 F Right 28 3 164 998 88 CC15 42 M Left 24 4 159 148 497 CC18 18 F Left 28 3 142 197 246 CC20 22 M Left/right 18 3 150 297 336 CC23 40 F Right 16 5 154 588 879 CC24 43 F Right 18 3 202 219 223 CC25 16 M Right 16 5 144 504 536 CC26 32 F Right 35 3 91 507 197 CC30 36 M Left 28 4 162 820 420 CC31 21 F Left 21 3 105 922 121 CC39 21 F Right 18 8 472 805 577 CC49 29 F Right 23 4 279 351 226 CC60 24 M Right 22 3 56 492 170 CC69 31 F Right 21 4 120 886 234 Mean ± SD 30.2 ± 11.8 21 ± 7.6 3.6 ± 1.5 170 ± 98 526 ± 295 328 ± 215 Location Number of bipolar
channelsNumber of
patientsSleep stage 1 Sleep stage 2 Sleep stage 3 Mean z [95% CI] p value Mean z [95% CI] p value Mean z [95% CI] p value Anterior hippocampus 48 12 0.14 [0.1, 0.18] 2.2 × 10-8 0.11 [0.064, 0.15] 8.2 × 10-6 0.15 [0.089, 0.22] 2.6 × 10-5 Posterior hippocampus 39 11 0.059 [0.016,0.1] 0.01 0.061 [0.019, 0.1] 0.0072 0.11 [0.044, 0.17] 0.0019 Cingulate 8 6 0.003 [−0.055, 0.061] 0.92 −0.0024 [−0.097,0.093] 0.96 0.083 [−0.033, 0.2] 0.21 Insula 5 4 0.043 [−0.09, 0.18] 0.56 −0.049 [−0.23, 0.13] 0.62 −0.18 [−0.51, 0.14] 0.33 Lateral temporal 46 13 0.083 [0.026, 0.14] 0.0068 −0.059 [−0.1, −0.017] 0.0081 −0.14 [−0.19, −0.081] 3 × 10-5 Lateral occipital 10 6 0.029 [−0.032,0.09] 0.38 −0.032 [−0.12, 0.06] 0.52 0.044 [−0.12, 0.21] 0.61 Lateral parietal 52 14 0.084 [0.044, 0.12] 0.0001 −0.019 [−0.065, 0.026] 0.41 0.033 [−0.018, 0.084] 0.21 Medial occipito-parietal 28 11 −0.014 [−0.067, 0.04] 0.62 0.0014 [−0.054,0.057] 0.96 0.067 [0.0089, 0.13] 0.032 Medial temporo-occipital 24 10 0.018 [−0.047, 0.083] 0.59 −0.032 [−0.083, 0.018] 0.23 −0.052 [−0.094, −0.011] 0.022 Orbitofrontal 13 5 0.089 [0.031, 0.15] 0.011 0.10 [0.063, 0.14] 0.0003 0.041 [−0.09, 0.17] 0.55 Paracentral 19 9 −0.014 [−0.092, 0.063] 0.73 −0.04 [−0.12, 0.036] 0.32 0.002 [−0.07, 0.074] 0.97 Prefrontal 38 8 0.060 [0.022, 0.097] 0.0037 0.036 [−0.011, 0.083] 0.14 0.067 [0.025, 0.11] 0.0053 The correlation
Extended Data Table 5-1
The percentage of correlated channels (bootstrapped) using the mean correlation and partial correlation in different sleep stages for each ROI. Download Table 5-1, DOCX file.
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