  We recently developed original electroencephalogram indices focusing on
microwaves of flattish period (named $\tau$), which correlated with volatile
anesthesia concentration in dogs. However, this mechanism remains unclear.
$\tau$ was defined as a subthreshold wave and burst wave was defined as an
above-threshold wave. This study shows that these indices well quantified the
morphological features of local field potential waveforms in mice, and made it
possible to discriminate the specific waveforms of the state of consciousness;
awake, shallow sleep, rapid eye movement sleep, and non-rapid eye movement
sleep. In addition, examination of $\tau$ suggested that microwaves are local
fluctuations of the electrode that can be formed for each data sampling, and
that its amplitude may increase with the degree of arousal.
