Figure 5. Power spectral density plots in the time-frequency domain for the slow sleep spindles measured in the ANT (left) and in the same time window in the frontal scalp derivations (right), separately for the SP(ripple) –top panels– and SP(pure) –bottom panels–, within the 1–450 Hz frequency range. The middle panels show the power spectral density differences between SP(ripple) and SP(pure). The timepoint “0” indicates the onset of sleep spindles in the ANT. Significant (p< 0.05 after FDR correction) time-frequency bins are circumscribed by the black lines. Increased time-frequency power was observed in the ripple and spindle band in the ANT but not in the scalp derivations. All time frequency maps were displayed from 2 to −2 dB, and frequency is represented in logarithmic scale.