Closing eyes during auditory memory retrieval modulates alpha rhythm but does not alter tau rhythm

The alpha power increase that occurs when the eyes are closed is one of the most well-known effects in human electrophysiology. In particular, previous psychological studies have investigated whether eye closure can boost memory performance under certain circumstances, providing contradictory evidence across sensory input modalities. Although alpha power is modulated during different phases of memory and these modulations are correlated with performance, few studies have reported on the relationship between eye closure, memory, and alpha-band power. The present study investigates the influence of eye closure while participants (n = 21) performed an auditory recognition memory task with spoken words during the recording of magnetoencephalography (MEG) data. Our results showed no evidence for a behavioural effect of eye closure in the performance of the task. In addition, electrophysiological responses to the stimuli showed the expected alpha event-related desynchronization (ERD) 0.5-1 s and a high-alpha/beta event-related synchronization (ERS) 1-2 s after word onset. The data showed the expected memory effect, i.e. remembered words elicited greater 10 Hz ERD than forgotten words in the brain regions typically associated with the language network, suggesting a modulation of tau rhythm. Eye closure modulated alpha rhythm only in posterior-parietal and occipital regions. The lack of interaction and the different localizations found for modulations of tau and classical alpha rhythms suggests that these rhythms play distinct functional roles in memory performance.