Analysis of the electrical activity in various brain regions for assessing differences in human functional states

The study presents an evaluation of the feasibility of using various EEG leads for calculating EEG signal metrics aimed at detecting differences in the EEG signal of a person in a state of concentration and a state of mind-wandering. The leads and metrics were selected based on an analysis of related studies focused on recognizing and assessing human states, such as concentration. Practical methods for calculating selected power and entropy metrics in various frequency bands are provided. The study uses a unique dataset containing EEG recordings for functional states of concentration at a point in the center of the forehead and background states of mind-wandering, including data from 17 participants. The assessment of the applicability of leads was based on the point-biserial correlation coefficient of the metric values with functional states, as well as a similar measure based on the difference in interquartile ranges of the metric values. It was shown that the most promising leads for application are prefrontal leads for calculating the signal entropy metric in the 0.3 to 30 Hz range, and occipital leads for calculating spectral power metrics in the α and θ ranges. For several metrics, not only absolute values are important, but also their ratios for different brain regions (prefrontal, central, and occipital). Among the relative values, the most promising is the ratio of metric values in the prefrontal leads to the corresponding values in the occipital leads. These metrics on the selected leads show significant but divergent changes between functional states for the participants in the sample.