Figure 1.

Characteristic spindles in a mPFC local field potential recording. A, An example 30 s trace of mPFC LFP during NREM sleep showing juxtaposed wideband signals (black) from one TRN tetrode and two mPFC tetrodes. One 6–18 Hz band-pass-filtered mPFC tetrode signal is also shown (red). Below is a power spectrogram generated from the same period showing transient increases in power within the spindle band (8–15 Hz, indicated by horizontal dashed white lines on the spectrogram) during identified spindle episodes, which are marked below the filtered LFP trace with black horizontal bars. B, Scatter plot of the durations of concurrent spindle events recorded on the two mPFC tetrodes shown in A. C, Cross-correlograms of spindle trough times; each line represents the mean across all mPFC-mPFC tetrode pairs in one rat. Individual spindle trough time cross-correlograms were calculated with a bin size of 2 ms and were mean normalized before averaging across tetrode pairs. D, Mean power spectrograms generated from the 50 longest and 50 shortest spindles from each rat, plotted in absolute time and time locked to the midspindle time point. The same color scale is used in both spectrograms. E, Example of how RST is calculated over a mPFC spindle. The band-pass-filtered mPFC LFP is shown, with detected spindle onset and offset times marked with vertical dashed lines. Absolute recording time is marked on the upper axis and the relative spindle time is shown on the lower axis. Spike times from a mPFC putative pyramidal cell are plotted with corresponding RST values. F, RST-normalized mean power spectrogram (n = 500 spindles from 6 rats, n = 3000 total). Dashed white lines indicate spindle onset and offset times. G, Mean instantaneous frequencies (dashed lines) shown over RST for 500 spindles from each rat (n = 3000 total) and overall mean (solid bold line).