2.4. EEG alpha reactivity analysis

EEG data from three occipital electrodes (O1, O2, and Oz) were used for the alpha reactivity analysis (Schumacher et al., 2020b, Wan et al., 2019). The PSD for the three electrodes was averaged across all included epochs and across the three electrodes for each condition separately (eyes-open and eyes-closed).

Alpha reactivity was calculated according to the following formula (Wan et al., 2019):

where alpha power was computed as the relative power within a frequency bin around the individual alpha peak frequency ±2 Hz. Individual alpha peak frequencies were calculated by locating the peak in the PSD in the extended alpha frequency band from 4 to 14 Hz (Babiloni et al., 2017, Babiloni et al., 2011) using the eyes-closed data. Individual alpha peak frequencies were used instead of the standard alpha frequency band to account for a shift of the alpha peak to slower frequencies in MCI patients (Bonanni et al., 2015, Schumacher et al., 2020a).