MapperEEG: A Topological Approach to Brain State Clustering in EEG Recordings

Electrical potential scalp recordings (Electroencephalograms-EEGs) are a common tool used to investigate brain activity. EEG is routinely used in clinical applications as well as in research studies thanks to its noninvasive nature, relatively inexpensive equipment, and high temporal resolution. But, EEG is prone to contamination from movement artifacts and signals from external sources. Thus, it requires advanced signal processing and mathematical analysis methods in tasks requiring brain state identification. Recently, tools from topological data analysis have been used successfully across many domains, including brain research, however these uses have been limited to fMRI datasets. We introduce the topological tool MapperEEG (M-EEG) and provide an example of it's ability to separate different brain states during a simple finger tapping teaming task without any pre-labeling or prior knowledge. M-EEG uses the power spectral density applied to traditional EEG frequency bands combined with the Mapper algorithm from topological data analysis to capture the underlying structure of the data and represent that structure as a graph in two-dimensional space. This tool provides clear separation (clustering) of states during different conditions of the experiment (syncopated vs. synchronized) and we demonstrate that M-EEG outperforms other clustering methods when applied to EEG data.