title: Delayed enhancement of multitasking performance: Effects of anodal transcranial direct current stimulation on the prefrontal cortex.
abstract: BACKGROUND
  The dorsolateral prefrontal cortex (DLPFC) has been proposed to play an important role in neural processes that underlie multitasking performance. However, this claim is underexplored in terms of direct causal evidence.
  
  
  OBJECTIVE
  The current study aimed to delineate the causal involvement of the DLPFC during multitasking by modulating neural activity with transcranial direct current stimulation (tDCS) prior to engagement in a demanding multitasking paradigm.
  
  
  METHODS
  The study is a single-blind, crossover, sham-controlled experiment. Anodal tDCS or sham tDCS was applied over left DLPFC in forty-one healthy young adults (aged 18-35 years) immediately before they engaged in a 3-D video game designed to assess multitasking performance. Participants were separated into three subgroups: real-sham (i.e., real tDCS in the first session, followed by sham tDCS in the second session 1 h later), sham-real (sham tDCS first session, real tDCS second session), and sham-sham (sham tDCS in both sessions).
  
  
  RESULTS
  The real-sham group showed enhanced multitasking performance and decreased multitasking cost during the second session, compared to first session, suggesting delayed cognitive benefits of tDCS. Interestingly, performance benefits were observed only for multitasking and not on a single-task version of the game. No significant changes were found between the first and second sessions for either the sham-real or the sham-sham groups.
  
  
  CONCLUSIONS
  These results suggest a causal role of left prefrontal cortex in facilitating the simultaneous performance of more than one task, or multitasking. Moreover, these findings reveal that anodal tDCS may have delayed benefits that reflect an enhanced rate of learning.
authors.affiliation: Department of Neurology, University of California, San Francisco, San Francisco, CA, USA; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Laboratory of Neurophysiology, Taipei Veterans General Hospital, Taipei, Taiwan; Integrated Brain Research Laboratory, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Wan-Yu
authors.initials: WY
authors.lastname: Hsu
authors.affiliation: Department of Neurology, University of California, San Francisco, San Francisco, CA, USA.
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Zanto
authors.affiliation: Department of Neurology, University of California, San Francisco, San Francisco, CA, USA.
authors.forename: Joaquin A
authors.initials: JA
authors.lastname: Anguera
authors.affiliation: Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Department of Neurology, National Yang-Ming University, Taipei, Taiwan; Institute of Physiology, National Yang-Ming University, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan; Laboratory of Neurophysiology, Taipei Veterans General Hospital, Taipei, Taiwan; Integrated Brain Research Laboratory, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Yung-Yang
authors.initials: YY
authors.lastname: Lin
authors.affiliation: Department of Neurology, University of California, San Francisco, San Francisco, CA, USA; Departments of Physiology and Psychiatry, University of California, San Francisco, San Francisco, California, USA. Electronic address: adam.gazzaley@ucsf.edu.
authors.forename: Adam
authors.initials: A
authors.lastname: Gazzaley
mesh_terms: D000293:Adolescent; D000328:Adult; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000502:physiology*; D016037:Single-Blind Method; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
keywords: Attention; Dorsolateral prefrontal cortex; Multitasking; Transcranial direct current stimulation