Lateralised modulation of posterior alpha oscillations by closed loop auditory stimulation during memory retention.

Abstract

Alpha oscillations have been implicated in the maintenance of working memory representations. Notably, when memorised content is spatially lateralised, the power of posterior alpha activity exhibits corresponding lateralisation during the retention interval, consistent with the retinotopic organisation of the visual cortex. Beyond power, alpha frequency has also been linked to memory performan ce, with faster alpha rhythms associated with enhanced retention. These findings position alpha oscillations as a promising target for neuromodulation. In this study, we demonstrate that although alpha frequency is not typically lateralised in a retinotopic manner during working memory retention, such lateralisation can be externally induced. Using alpha closed-loop auditory stimulation targeted to opposite alpha phases on opposite cortices and leveraging the previously demonstrated phase-dependent modulation of alpha oscillations' frequency by sound, we successfully modulated alpha frequency asymmetrically between the visual cortices. The extent of induced frequency lateralisation was associated with the behavioural asymmetry in task performance.