Enhancing visual working memory in schizophrenia: effects of frontoparietal theta tACS in low-performing patients
Journal
Schizophrenia
Journal Volume
10
Journal Issue
1
ISSN
2754-6993
Date Issued
2024-10-26
Author(s)
Wang, Jiunn-Kae
Sahu, Prangya Parimita
Ku, Hsiao-Lun
Lo, Yu-Hui
Chen, Ying-Ru
Lin, Che-Yin
Abstract
Schizophrenia is a complex neuro-psychiatric disorder including positive symptoms, negative symptoms, and cognitive deficits. A key cognitive dysfunction in schizophrenia is a deficit in visual working memory (VWM). VWM involves three distinct stages: encoding, maintenance, and retrieval. The deficit in any one stage would produce the same symptom (i.e., poor VWM), although their causes are not the same. In this study, we used a retro-cue VWM task that provides helpful cues at different stages: early in maintenance (early cue), late in maintenance (late cue), or during retrieval (retrieval cue). This modification would help “tag” or identify the cognitive stage(s) most responsible for impaired VWM performance in schizophrenia. Additionally, we took advantage of this tagging feature and applied 6 Hz transcranial alternating current stimulation (tACS) over the right dorsolateral prefrontal cortex (DLPFC) and right posterior parietal cortex (PPC)—which has previously been shown to enhance VWM in low-performing healthy individuals—to examine whether tACS would improve a specific stage or all stages of VWM processing in schizophrenia. We observed that cues significantly enhanced performance in low-performing patients, who benefited equally from early and late maintenance cues, but not from retrieval cues. These low-performers also responded well to theta tACS in their overall VWM performance as opposed to a specific VWM stage. No improvement effect was observed in high-performing patients for both retro cue and tACS. Together, our data suggest that 1) low-performing patients’ VWM deficits likely stem from poor memory consolidation rather than retrieval, 2) right frontoparietal theta tACS can improve low-performing patients’ VWM performance, and 3) such facilitatory tACS effect is not selective of a specific VWM stage and thus is likely driven by an improvement in overall visual attention.
Subjects
chlorpromazine
adult
aged
analysis of variance
Article
Beck Depression Inventory
cognition
cognitive defect
controlled study
depression
disease association
dorsolateral prefrontal cortex
female
human
intelligence quotient
male
memory consolidation
memory disorder
Montreal cognitive assessment
Positive and Negative Syndrome Scale
posterior parietal cortex
potential difference
reaction time
schizophrenia
theta rhythm
transcranial alternating current stimulation
visual memory
Wechsler adult intelligence scale
working memory
Publisher
Springer Science and Business Media LLC
Type
journal article