Similar to the Rodent Sleep Scoring detector, the Rodent Sleep Scoring 2 detector uses one or two EEG signals, along with EMG and activity data to automatically assign a vigilance stage to a user defined epoch. However, this module provides greater user control over how the algorithm scores the recording for greater accuracy in scoring rodent sleep/wakefulness.
Unlike the original Rodent Sleep Scoring detector, which calculates the periodogram over the entire user defined epoch, the Rodent Sleep Scoring 2 detector calculates the periodogram over 1 second sub-epochs, assigning each a unique sleep stage. Once all 1 second epochs are scored, a sleep stage will be determined for the entire user defined epoch (e.g. 10sec or 30sec) and scored based on the stage with the majority of 1 second epochs.
The algorithm will assess each individual second of the recording and determine the probability of Wake, Paradoxical Sleep (PS) and Slow Wave Sleep (SWS) based on the following criteria:
- Delta Power (Delta/Total)
Used to identify SWS.
- Theta Power (Theta/Delta)
Used to identify PS.
- EMG Power (Root Mean Square)
Used to identify Wake.
- Contribution factors (User-defined %)
- Stage transition probabilities (User-defined %).
- Epochs with Activity >0 are scored as Active Wake.
If the EEG or EMG amplitude exceeds the artifact threshold or has any bad samples (i.e. signal dropout) the 1 second epoch is scored as Artifact.
Understanding the Detection Level Sliders
The Delta Power Levels will be used as an example to better understand the use of the Detection Level Sliders.
- First, the algorithm will compute the Delta/Total power ratio for each individual second of the recording.
- Then, it will calculate the average Delta/Total ratio, after discarding the lowest 10% and the highest 30%.
- In the example below, the probability of SWS will be maximal if the Delta/Total power of a 1-second epoch is greater than 1.45 times the average that we have calculated above.