Optimizing detection and analysis of slow waves in sleep EEG

- We introduce an open-source toolbox for individual detection and analysis of slow waves in sleep electroencephalography.
- Novel and previously applied automatic detection algorithms are introduced and explored.
- Individual slow waves are detected in sleep recordings from participants along a large search-space of parameter settings.
- Properties of detected slow waves are compared across parameter settings on a range of outcome measures of interest.
- Visualization options for toolbox users are introduced, including the possibility to manual score sleep.

BackgroundAnalysis of individual slow waves in EEG recording during sleep provides both greater sensitivity and specificity compared to spectral power measures. However, parameters for detection and analysis have not been widely explored and validated.New methodWe present a new, open-source, Matlab based, toolbox for the automatic detection and analysis of slow waves; with adjustable parameter settings, as well as manual correction and exploration of the results using a multi-faceted visualization tool.ResultsWe explore a large search space of parameter settings for slow wave detection and measure their effects on a selection of outcome parameters. Every choice of parameter setting had some effect on at least one outcome parameter. In general, the largest effect sizes were found when choosing the EEG reference, type of canonical waveform, and amplitude thresholding.Comparison with existing method: Previously published methods accurately detect large, global waves but are conservative and miss the detection of smaller amplitude, local slow waves. The toolbox has additional benefits in terms of speed, user-interface, and visualization options to compare and contrast slow waves.ConclusionsThe exploration of parameter settings in the toolbox highlights the importance of careful selection of detectionMethodsThe sensitivity and specificity of the automated detection can be improved by manually adding or deleting entire waves and or specific channels using the toolbox visualization functions. The toolbox standardizes the detection procedure, sets the stage for reliable results and comparisons and is easy to use without previous programming experience.