Supplementary Figure 5: Unclassified brain state induced by optogenetic activation of cholinergic BF neurons.

a. Example trials in which laser stimulation induced wakefulness of ChAT-ChR2 mice. Shown are EEG power spectrum, EEG traces during selected periods (indicated by boxes), and EMG trace in each trial. Blue bar, period of laser stimulation. Note the increase in EMG activity upon laser stimulation.

b. Similar to a, but for trials in which laser stimulation induced EEG desynchronization but no change in EMG.

c. Average EEG power spectra during natural wake, NREM and REM sleep, and during laser stimulation in trials without EMG change (see examples in b). Note that the EEG power spectrum in these trials is different from any of the natural brain states, thus the brain state was left unclassified in our study. The peak at ~6 Hz (lower than the frequency of theta band observed in natural REM sleep) has also been observed in the study of Han et al.³⁸, and in their study the brain state was classified as REM sleep.

d. Probability of wake, NREM, REM, and unclassified states before, during, and after laser stimulation, averaged across 5 ChAT-ChR2 mice (same as Fig. 4c, but including probability of unclassified state).