SUPPLEMENTARY METHODS Detection of phasic REM (original) (raw)

following. First, LFP trace during REM epochs were band-pass filtered (5-12 Hz), yielding y(t). Amplitude of theta oscillations were derived from Hilbert transform of y(t), and peaks of theta oscillations were detected as the positive to negative zero crossings of the derivative dy/dt. Inter-peak intervals were smoothed using an eleven-sample rectangular kernel. Candidate epochs were detected if smoothed inter-peak intervals were shorter than 10 percentile of smoothed inter-peak intervals. The candidate epochs were identified as phasic REM epochs if the following criteria were all fulfilled. (1) Duration of an epoch was longer than 900 msec. (2) Minimum of smoothed inter-peak intervals during an epoch was shorter than 5 percentile of smoothed inter-spike intervals. (3) Mean amplitude of theta oscillations during an epoch was larger than mean amplitude of theta oscillations during the entire REM sleep. A total of 5844 sec (3.68 % of REM sleep episodes) was identified as phasic REM ep...