title: Unidirectional visual motion adaptation induces reciprocal inhibition of human early visual cortex excitability.
abstract: OBJECTIVE
  Behavioural observations provided by the waterfall illusion suggest that motion perception is mediated by a comparison of responsiveness of directional selective neurones. These are proposed to be optimally tuned for motion detection in different directions. Critically however, despite the behavioural observations, direct evidence of this relationship at a cortical level in humans is lacking. By utilising the state dependant properties of transcranial magnetic stimulation (TMS), one can probe the excitability of specific neuronal populations using the perceptual phenomenon of phosphenes.
  
  
  METHODS
  We exposed subjects to unidirectional visual motion adaptation and subsequently simultaneously measured early visual cortex (V1) excitability whilst viewing motion in the adapted and non-adapted direction.
  
  
  RESULTS
  Following adaptation, the probability of perceiving a phosphene whilst viewing motion in the adapted direction was diminished reflecting a reduction in V1 excitability. Conversely, V1 excitability was enhanced whilst viewing motion in the opposite direction to that used for adaptation.
  
  
  CONCLUSIONS
  Our results provide support that in humans a process of reciprocal inhibition between oppositely tuned directionally selective neurones in V1 facilitates motion perception.
  
  
  CONCLUSIONS
  This paradigm affords a unique opportunity to investigate changes in cortical excitability following peripheral vestibular disorders.
authors.affiliation: Academic Department of Neuro-Otology, Imperial College London, Charing Cross Hospital Campus, Fulham Palace Road, London W6 8RF, United Kingdom.
authors.forename: Q
authors.initials: Q
authors.lastname: Arshad
authors.affiliation: Academic Department of Neuro-Otology, Imperial College London, Charing Cross Hospital Campus, Fulham Palace Road, London W6 8RF, United Kingdom.
authors.forename: Y
authors.initials: Y
authors.lastname: Nigmatullina
authors.affiliation: Academic Department of Neuro-Otology, Imperial College London, Charing Cross Hospital Campus, Fulham Palace Road, London W6 8RF, United Kingdom. Electronic address: a.bronstein@imperial.ac.uk.
authors.forename: A M
authors.initials: AM
authors.lastname: Bronstein
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D010719:Phosphenes / Q000502:physiology*; D010775:Photic Stimulation; D050781:Transcranial Magnetic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult
keywords: Reciprocal inhibition; Transcranial magnetic stimulation; V1; Visual motion adaptation; Waterfall illusion