title: Modulating the interference effect on spatial working memory by applying transcranial direct current stimulation over the right dorsolateral prefrontal cortex.
abstract: Spatial working memory (SWM) is the ability to temporarily store and manipulate spatial information. It has a limited capacity and is quite vulnerable to interference. Dorsolateral prefrontal cortex (DLPFC) has been shown to be a part of the SWM network but its specific functional role still remains unknown. Here we applied transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique that provides polarity-specific stimulation over the targeted region, to investigate the specific role of the right DLPFC in resolving interference in SWM. A forward- and backward-recall computerized Corsi Block Tapping task (CBT), both with and without a concurrent motor interference task (the modified Luria manual sequencing task) was used to measure SWM capacity and reaction time. The results showed that motor interference impeded accuracy and prolonged reaction time in forward and backward recall for SWM. Anodal tDCS over right DLPFC yielded the tendency to shorten participants' reaction time in the conditions with interference (forward with interference, and backward with interference). Most importantly, anodal tDCS significantly improved participants' SWM span when cognitive demand was the highest (the "backward-recall with motor interference" condition). These results suggest that (1) the right DLPFC plays a crucial role in dealing with the cross-domain motor interference for spatial working memory and (2) the anodal tDCS over right DLPFC improved SWM capacity particularly when task difficulty demands more complex mental manipulations that could be due to the facilitatory effect of anodal tDCS which enhanced the DLPFC function within central executive system at the top-down attentional level.
authors.affiliation: Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, #138 Sheng Li Road, Tainan 701, Taiwan; Department of Neurology, National Cheng Kung University College of Medicine and Hospital, Dou-Liou Branch, Yunlin, Taiwan; Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, #138 Sheng Li Road, Tainan 701, Taiwan.
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Wu
authors.affiliation: Institute of Cognitive Neuroscience, National Central University, #300, Jhongda Road, Jhongli City 320, Taiwan; Taipei Medical University - Shuang Ho Hospital, Brain and Consciousness Research Center, New Taipei City, Taiwan.
authors.forename: Philip
authors.initials: P
authors.lastname: Tseng
authors.affiliation: Institute of Cognitive Neuroscience, National Central University, #300, Jhongda Road, Jhongli City 320, Taiwan.
authors.forename: Chi-Fu
authors.initials: CF
authors.lastname: Chang
authors.affiliation: Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, #138 Sheng Li Road, Tainan 701, Taiwan.
authors.forename: Ming-Chyi
authors.initials: MC
authors.lastname: Pai
authors.affiliation: Department of Pharmacology, College of Medicine, National Cheng Kung University, #1, University Road, Tainan 701, Taiwan.
authors.forename: Kuei-Sen
authors.initials: KS
authors.lastname: Hsu
authors.affiliation: Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, #138 Sheng Li Road, Tainan 701, Taiwan. Electronic address: cxl45@mail.ncku.edu.tw.
authors.forename: Chou-Ching
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Institute of Cognitive Neuroscience, National Central University, #300, Jhongda Road, Jhongli City 320, Taiwan. Electronic address: chijuan@cc.ncu.edu.tw.
authors.forename: Chi-Hung
authors.initials: CH
authors.lastname: Juan
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000502:physiology*; D011930:Reaction Time; D065908:Transcranial Direct Current Stimulation / Q000379:methods; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
keywords: Corsi Block Tapping task; Dorsolateral prefrontal cortex; Interference effect; Spatial working memory; Top-down control; Transcranial direct current stimulation; Visual short-term memory; Visual working memory; Visuospatial working memory