title: Within-session repeated a-tDCS: the effects of repetition rate and inter-stimulus interval on corticospinal excitability and motor performance.
abstract: OBJECTIVE
  This study investigated the effect of rate and stimulation interval of anodal transcranial direct current stimulation (a-tDCS) on CSE and motor performance.
  
  
  METHODS
  Twelve healthy individuals participated in this study. CSE was assessed before and after five experimental conditions of one, two or three applications of 10 min of a-tDCS with an interval of 5 or 25 min. a-tDCS was applied with a constant current density of 0.016 mA/cm(2). Purdue pegboard-test was selected for motor performance assessment.
  
  
  RESULTS
  Compared to single 10 min stimulation, the magnitude of the within-session repeated a-tDCS induced excitability was enhanced significantly after the second stimulation was performed with an interval of 25 min, but not 5 min. However, by increasing the number of a-tDCS to three repetitions the CSE was significantly increased and lasted for 2h with both 5 and 25 min intervals. Furthermore, CSE enhancement remained significant for up to 24h for within session a-tDCS repetitions with 25 min intervals. Likewise, significant improvement was seen in motor performance following three times repetition with 25 min inter-stimulus intervals.
  
  
  CONCLUSIONS
  The results suggest that within session repeated a-tDCS with longer intervals within the lasting effects of the previous stimulations are preferable for increasing induced excitability changes with longer lasting effects.
  
  
  CONCLUSIONS
  It is of particular importance to increase the a-tDCS lasting effects to consolidate the neuroplastic CSE changes.
authors.affiliation: Department of Physiotherapy, School of Primary Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia. Electronic address: andisheh.bastanijahromi@monash.edu.
authors.forename: A
authors.initials: A
authors.lastname: Bastani
authors.affiliation: Department of Physiotherapy, School of Primary Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Jaberzadeh
mesh_terms: D000293:Adolescent; D000328:Adult; D004566:Electrodes; D055724:Electrophysiological Phenomena; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D015203:Reproducibility of Results; D065908:Transcranial Direct Current Stimulation / Q000009:adverse effects / Q000379:methods*; D055815:Young Adult
keywords: Non-invasive brain stimulation; Optimal tDCS parameter; Plasticity; Transcranial direct current stimulation; Transcranial magnetic stimulation