Vigilance State
Vigilance state is the behavioral condition of the animal during a recording — awake, non-REM sleep, REM sleep or anesthetized — inferred from EEG spectra, muscle tone and movement, and the label every other measurement is scored against.
Neural activity differs by state in rate, rhythm and correlation, so a comparison across sessions or animals that ignores state compares states, not conditions. Staging uses EEG power ratios such as theta to delta, EMG amplitude and locomotion, by hand or with a classifier.
The recording chain decides whether staging is trustworthy. State should be scored from a signal independent of the one being analyzed — EMG leads and a head-mounted accelerometer on the same implant, as in the rat EEG study, rather than the EEG itself — so that the labels and the result are not circular. A skull-surface EEG array records state over months with no craniotomy, and pairs with a penetrating probe when units and state are needed on the same clock — the arrangement the EEG series and the X-Series headstages, with their on-board accelerometer, are built for.
Typical values
| States | awake · non-REM sleep · REM sleep · anesthetized |
|---|---|
| Staging signals | EEG power ratios (theta/delta), EMG amplitude, locomotion |
| Rule | score state from a signal independent of the one analyzed |