Sleep Spindles as an Electrographic Element: Description and Automatic Detection Methods

Figure 6

Late slow and early fast spindles with the Slow Wave Oscillation (SWO). (a) Grand mean averages (±SEM) of original EEG in (top) 12 centroparietal channels across all detected fast spindles, in (middle) 12 frontocentral channels across all detected slow spindles, and (bottom) in 8 frontocentral channels across all detected slow oscillations. Note that spindles are averaged independently of whether an SWO was present. Averaging was performed with reference to the deepest, that is, most negative, trough in the filtered signal (). Asterisks (and arrows) indicate a significant () positive and negative slow potential shift underlying early fast and late slow spindles, respectively, in the interval between 300 ms before and 300 ms after the spindle peak. (b) Potential shifts underlying early fast spindles and late slow spindles. Mean (±SEM) slow potential shifts underlying (top) early fast spindles at central, centroparietal, and parietal electrodes and (bottom) late slow spindles at frontal, frontocentral, and central electrodes. Asterisks indicate significant differences between topographies in positive and negative slow potential shifts, respectively (, ). Modified from [31].

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