Sensory stimulation enhances visual working memory capacity

Abstract

Visual working memory (vWM) plays a crucial role in visual information processing and higher cognitive functions; however, it has a very limited capacity. Recently, several studies have successfully modulated vWM capacity in humans using entrainment with transcranial alternate current stimulation (tACS) by targeting parietal theta in a frequency-specific manner. In the current study, we aim to expand upon these findings by utilizing sensory instead of electrical stimulation. Across six behavioral experiments (combined N=209), we applied rhythmic visual and auditory sensory stimulation at 4 Hz and 7 Hz, aiming to modulate vWM capacity. Collectively, the results showed an overall robust improvement with sensory stimulation at either frequency, compared to baseline. However, contrary to our prediction, 7 Hz stimulation tended to slightly outperform 4 Hz stimulation. Importantly, the observed facilitatory effect was mainly driven by the low-capacity sub-group of participants. Follow-up experiments using the Attention Network Test (ANT) and pupillometry measures did not find evidence that this effect could be directly attributed to modulation of phasic or tonic arousal. We speculate that our results differed from those obtained with tACS due to targeting functionally different theta oscillations, or the modulation of participants' temporal expectations.

This work has been supported by the grant from the Agency for Management of University and Research Grants (2021 SGR 00911), Ministerio de Ciencia e Innovación (PID2022-137277NB-I00 AEI/FEDER), and was part of the PID2022-137277NB-I00 project financed by MICIU/AEI/10.13039/501100011033 and by 'ERDF A way of making Europe'. I.P. was supported by a fellowship from 'la Caixa' Foundation (ID 100010434; fellowship code LCF/BQ/DI18/11660026), which has received funding from the European Unions Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 713673. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. We would also like to thank Pau Castro San Cristóbal, Georgios Chatzopoulos, Balázs Juhász, and Mitchell Walters, who helped with setting up the protocols and the data collection in individual experiments.