Figure 1.
Illustration of the slow wave events detection method and example of Th/Td distributions.
A. Left: 3D reconstructed implantation of one subject. The red circle marks the approximate position of the scalp reference contact. Right: Example of scalp slow oscillation and one of its intracranial correlates (note the polarity inversion of the intracranial signal with respect to scalp). All signals are filtered in the band 0.1–4.0 Hz. The hyperpolarization and depolarization onsets have been marked for the scalp signal. The duration of the hyperpolarization (Th) and depolarization (Td) phases of each oscillation is shown as well (black and gray horizontal lines, respectively). B. Segment of scalp signal presenting six detected slow waves. For the second detection, the Th and Td of the detected intracranial correlates have been plotted. The numbers stand for contacts of the same electrode. This particular implantation consisted of 55 contacts distributed in 11 electrodes, 6 electrodes (n.1–6, 30 contacts) in the left frontal lobe and 5 (n.7–11, 25 contacts) in the left temporal lobe. The contacts in the frontal lobe cover from the F1, F2 and orbital regions to interior regions like the anterior part of the cingulated gyrus, the insula and the cortex subcallosum. The electrodes in the temporal lobe cover different cortical and white matter regions as well as deeper structures like the amygdala and the hippocampus. C. Examples of typical Probability Density Functions of Th and Td obtained for a single subject. For the construction of the pdfs only the intracranially measured Th and Td were taken into account. mark the position of the fast/slow hyperpolarization/depolarization times of the subject.
Figure 2.
Examples of fast/slow hyperpolarization/depolarization slow waves.
A. Superposition of filtered signals (0.1–4 Hz) of scalp EEG recordings (FP1) corresponding to 300 slow waves showing fast hyperpolarization (top) and 300 slow waves showing slow hyperpolarization (bottom) of a single subject (S1). The thick red line is the average profile of the shown filtered signals. A vertical dashed line marks the position of the hyperpolarization onset of the average signal. The graphs in the right panels indicate the region in the mode Th distribution from which the events in the figures have been drawn. B. Superposition of filtered signals (0.1–4 Hz) of scalp EEG recordings (FP1) corresponding to 300 slow waves showing fast depolarization (top) and 300 slow waves showing slow depolarization (bottom) of subject S1. The thick red line is the average profile of the shown filtered signals. The vertical dashed line marks the end of the depolarization (as has been defined in the text). The graphs in the right panels indicate the region in the mode Td distribution from which the events in the figure have been drawn.
Figure 3.
Distributions of mode Th/d and study of the correlation between hyperpolarization and depolarization times.
A. Mode Th/d Probability Density Functions of a subject and mode Th/d for each of the events detected in a whole night of sleep (5685 events were detected in that particular night of which only the first 5000 are shown). mark the position of the typical fast/slow hyperpolarization/depolarization mode times of the events of the subject. B. Left: Td vs. Th for a single subject. Right: mode Td vs. mode Th for a single subject. (A logarithmic scale has been used in both cases for the density color coding). C. Probability Density Function of (Th+Td) and (mode Th+mode Td). The continuous lines correspond to the estimated PDF using KDE (See Materials and Methods).
Figure 4.
Propagation of the slow waves.
A. Filtered (0.1–4 Hz) signals of intracranial EEG contacts of one global slow wave event ordered as a function of the position of the minimum (red dots). The vertical dashed line marks the position of the minimum of the first detection. B. Three examples of local propagation in the temporal lobe. Each example corresponds to a different slow wave event. In all cases the signals are linked to the position of the recording contacts in the brain, represented by red cubes.
Figure 5.
Results of the propagation study. A. Left: First and last hubs of the H-wave propagation of all studied subjects superimposed on the same reference brain (Top and left views). Right: First and last hubs of the D-wave propagation of all studied subjects superimposed on the same reference brain (Top and left views). The little black dots correspond to the implanted contacts not presenting a first/last hub character. These are shown to illustrate the total coverage of the sum of the individual implantations. Please note the final coverage of the sum of all the implantations is not homogeneous with 295 (71%) contacts is the left hemisphere and 122 (29%) in the right hemisphere. B. Number of first/last hubs found in each of the following regions: Frontal (Fro), Parietal (Par), Insula (Ins), Cingulate cortex (Cin), Temporal (Tem), Occipital (Occ) and Striatum (Str).