Figure 9.

Spatiotemporal heterogeneity in intracranial correlates of scalp-detected STW (example Patient 18). The variation in the z score with respect to the control segments in 22 channels in the high δ (2-4 Hz, top) and low-ripple (80-120 Hz, bottom) bands during the 76 scalp STW events is presented. Segments have been sorted according to the z scores of the high δ frequency band in channel RCp3-4, which has an important increase in both bands. In 16 of 22 channels, the effect size is larger than zero in the 2-4 Hz band, but only 4 channels have a large effect size (LH6-7, RCp2-3, RCp3-4, RCp4-5). The largest effect size (d = 2.06) is observed in channel RCp3-4, and the z score of the power increase for the different events in this channel shows high temporal variability as it ranges from −0.17 to 2.59 (mean ± SD, 0.98 ± 0.48). The correlation coefficient of the time-series of the z score of the power increase between channels (i.e., between rows) is not very high, indicating an important spatial variability. The neighboring channel RCp4-5 shows a correlation coefficient (ρ = 0.82) statistically different from zero (p < 10⁻⁴ after correction for multiple comparisons), as do RCp2-3 (ρ = 0.53, p < 10⁻⁴) and LH6-7 (ρ = 0.44, p = 0.005). In the low-ripple band (80-120 Hz) there are 21 of 22 channels with a positive effect size, and 8 with a large effect size (LH5-6, LH6-7, all RCp channels, and RPC1-2, RPC2-3). Finally, the behavior between the different bands is also variable; the correlation coefficient of the variability between bands (2-4 Hz and 80-120 Hz) is only significantly different from zero for RPC3-4 (ρ = 0.44, p = 0.005). LH, Left hippocampus (deep contacts 1-5 in the hippocampus, superficial contacts from 6 to 10 in middle temporal gyrus); RCa, targeting right anterior cingulate gyrus (deep contacts 1-4 in the anterior cingulate gyrus, superficial contacts 5 and 6 in the middle frontal gyrus); RCm, targeting right middle cingulate gyrus (deep contacts 1-3 in the middle cingulate gyrus, superficial contacts 4-5 in the middle frontal gyrus); RCp, targeting right posterior cingulate gyrus (deep contacts 1-3 in the medial segment of precentral gyrus, superficial contacts 4 and 5 in postcentral gyrus); RPC, targeting right precuneus (deep contacts 1 and 2 in the precuneus, superficial contacts 3-5 in the superior parietal lobule, and 6 in supramarginal gyrus). Abbreviations: freq, frequencies.