Frontoparietal theta tACS nonselectively enhances encoding, maintenance, and retrieval stages in visuospatial working memory. (November 2021)

• Record Type: Journal Article
• Authors: Sahu, Prangya Parimita; Tseng, Philip
• Is Part Of: Neuroscience research. Volume 172(2021)
• Page Start: 41
• Page End: 50
• Publication Date: 2021-11
• Subjects: Transcranial alternating current stimulation (tACS) -- Electric brain stimulation -- Transcranial direct current stimulation -- Neural oscillation -- Neural entrainment -- Working memory; Neurosciences -- Research -- Periodicals; Neurosciences -- Research -- Japan -- Periodicals; Neurology -- Periodicals; Neurosciences -- Periodicals; Neurosciences -- Recherche -- Périodiques; Neurosciences -- Recherche -- Japon -- Périodiques; Neurosciences -- Research; Japan; Periodicals; 612.8
• DOI: 10.1016/j.neures.2021.05.005
• Languages: English
• ISSNs: 0168-0102

Abstract

Highlights: We combined retro-cuing and theta tACS to investigate if tACS-induced improvement is stage-specific. Theta tACS created overall improvement, and is not stage-specific. Partial evidence for low-performers benefiting more from theta tACS. Low- and high-performers differed mostly in the late-maintenance stage. Negative correlation between age and VWM performance is observed. Abstract: Neurobiological and cognitive evidence suggests that working memory is processed through three distinctive and well-characterized phases: encoding, maintenance, and retrieval. Several studies have reported that applying theta transcranial alternating current stimulation (tACS) to the right prefrontal and parietal cortices can significantly improve visual working memory performance. However, it remains unclear whether the facilitative effect of tACS on visual working memory is due to a domain-general or stage-specific process. In this study, we combined pre-task right frontoparietal theta tACS (6 Hz, 15 min) with a stage-specific change detection paradigm that provided retro-cues during various stages of working memory. This stage-specific tagging via the use of retro-cues enabled us to probe whether theta tACS would create a nonspecific/additive effect that is equal in magnitude across all cognitive stages or would create a stage-specific effect that is interactive with the retro-cue in a particular stage (e.g., maintenance, retrieval). We observed significant retro-cue and theta tACS effects on visual working memory performance, but no interaction between them. This finding suggests that the aforementioned two factors can facilitate visual working memory processing independently in an additive manner. Furthermore, low-performers benefited more from tACS, and their VWM deficit seemed to have originated from the second half of the memory retention stage, which possibly suggests faster memory decay as the key to poor VWM performance. Together, we conclude that frontoparietal theta tACS likely creates a domain-general boost in visual attention, which in turn benefits overall visual working memory processes that are not specific to the information maintenance or retrieval stages.