EEG microstates: Functional significance and short-term test-retest reliability

EEG microstates, reflecting discrete topographical organization of the signal power, may have clinical relevance; however, their functional significance and test-retest reliability remain unclear. To investigate canonical microstate classes pairwise transitions, to establish within-session reliability, we recorded 36-channel EEGs in 20 healthy volunteers during three eyes-closed conditions: mind-wandering, verbalization (silently repeating word ‘square’ every 2 s), visualization (visualizing a square s). Each condition lasted 3 min sequence conditions was repeated four times (two runs two repetitions). The participants' alertness sense effort experiment were rated using visual-analogue scales. data 2–20 Hz bandpass-filtered analysed into classes: A, B, C, D. C D persistently more dominant than A B all conditions. Of first-order parameters, average duration most reliable. class longer mind-wandering (106.8 ms) (102.2 or (99.8 ms), with concomitantly higher coverage (36.4% vs. 34.7% 35.2%), but otherwise there no clear association particular mental states. at beginning each run, together alpha power subjective ratings alertness. Only transitions between (from particular) significantly what would be expected from respective microstates' occurrences. transition probabilities, did not distinguish conditions, overall lower that parameters such as coverage. Further studies are needed classes. This might fruitfully achieved by looking complex syntax beyond transitions. ensure greater study designs should allow for shorter experimental regular breaks, particularly when microstates biomarkers.