title: Comparison of the effects of transcranial random noise stimulation and transcranial direct current stimulation on motor cortical excitability.
abstract: OBJECTIVE
  The objective of this study was to examine the effect of transcranial random noise stimulation (tRNS) with and without a direct current (DC) offset on motor cortical excitability and compare results to transcranial DC stimulation (tDCS).
  
  
  METHODS
  Fifteen healthy participants were tested in a within-subjects design. Motor-evoked potentials were measured before and up to 90 minutes after stimulation using transcranial magnetic stimulation. Five stimulation conditions were examined: sham, 1-mA tDCS, 2-mA tDCS, 2-mA tRNS (with no DC offset), and 2-mA tRNS + 1-mA DC offset.
  
  
  RESULTS
  There were no significant differences between the stimulation conditions. An analysis of individual stimulation conditions found that there was a significant increase in motor-evoked potential amplitudes after 1-mA tDCS, 2-mA tDCS, and 2-mA tRNS + DC offset when compared with baseline. Sham and 2-mA tRNS did not result in changes in cortical excitability.
  
  
  CONCLUSIONS
  Although differences between the stimulation conditions did not reach a statistical significance, the findings suggest that stimulation involving a DC (tDCS and tRNS + DC offset) but not solely tRNS is more likely to lead to increases in cortical excitability.
authors.affiliation: From the *School of Psychiatry, University of New South Wales, Black Dog Institute, †Neuroscience Research Australia and School of Medical Sciences, University of New South Wales, and ‡Department of Psychiatry, St George Hospital, Sydney, Australia.
authors.forename: Kerrie-Anne
authors.initials: KA
authors.lastname: Ho
authors.forename: Janet L
authors.initials: JL
authors.lastname: Taylor
authors.forename: Colleen K
authors.initials: CK
authors.lastname: Loo
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation / Q000379:methods*; D055815:Young Adult