title: Transcranial alternating current stimulation (tACS) modulates cortical excitability as assessed by TMS-induced phosphene thresholds.
abstract: OBJECTIVE
  Recent developments in transcranial alternating current stimulation (tACS) provide a powerful approach to establish the functional roles of neuronal oscillatory activities in the human brain. Here, we investigated whether tACS can reach and modulate the excitability of the visual cortex in a frequency-dependent manner.
  
  
  METHODS
  We measured the cortical excitability of the visual cortex using single pulse transcranial magnetic stimulation (TMS) while delivering tACS to the occipital region at different frequencies (5, 10, 20 and 40 Hz).
  
  
  RESULTS
  We found that tACS at 20 Hz decreased TMS-phosphene threshold (i.e., increased the excitability of the visual cortex) during the stimulation, whereas other frequencies did not affect TMS-phosphene thresholds.
  
  
  CONCLUSIONS
  Our findings demonstrate direct interactions of tACS with the visual cortex in a frequency-dependent manner.
  
  
  CONCLUSIONS
  Our present work provides further demonstration of the potential of tACS as a method to selectively modulate the excitability of the visual cortex.
authors.affiliation: Institute of Cognitive Neuroscience & Dept. of Psychology, University College London, 17 Queen Square, WC1N 3AR London, United Kingdom. Electronic address: r.kanai@ucl.ac.uk.
authors.forename: Ryota
authors.initials: R
authors.lastname: Kanai
authors.affiliation: Department of Clinical Neurophysiology, Georg-August University, Robert Koch Straße 40, 37075 Göttingen, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Paulus
authors.affiliation: Institute of Cognitive Neuroscience & Dept. of Psychology, University College London, 17 Queen Square, WC1N 3AR London, United Kingdom.
authors.forename: Vincent
authors.initials: V
authors.lastname: Walsh
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D010719:Phosphenes / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult