title: Detection and discrimination of flicker contrast in migraine.
abstract: OBJECTIVE
  Flickering light is strongly aversive to many individuals with migraine. This study was designed to evaluate other abnormalities in the processing of temporally modulating visual stimulation.
  
  
  METHODS
  We measured psychophysical thresholds for detection of a flickering target and for the discrimination of suprathreshold flicker contrasts (increment thresholds) in 14 migraineurs and 14 healthy controls with and without prior adaptation to high-contrast flicker. Visual discomfort (aversion) thresholds were also assessed.
  
  
  RESULTS
  In the baseline (no adaptation) conditions, detection and discrimination thresholds did not differ significantly between groups. Following adaptation, flicker detection thresholds were elevated equivalently in both groups; however, discrimination thresholds were more strongly affected in migraineurs than in controls, showing greater elevation at moderate contrasts and greater threshold reduction (sensitisation) at high contrast (70%). Migraineurs also had significantly elevated discomfort scores, and these were significantly correlated with number of years with migraine.
  
  
  CONCLUSIONS
  We conclude that visual flicker not only causes discomfort but also exerts measurable effects on contrast processing in the visual pathways in migraine. The findings are discussed in the context of the existing literature on habituation, adaptation and contrast-gain control.
authors.affiliation: York University, Toronto, ON, Canada.
authors.forename: Olivera
authors.initials: O
authors.lastname: Karanovic
authors.forename: Michel
authors.initials: M
authors.lastname: Thabet
authors.forename: Hugh R
authors.initials: HR
authors.lastname: Wilson
authors.forename: Frances
authors.initials: F
authors.lastname: Wilkinson
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000293:Adolescent; D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D005425:Flicker Fusion / Q000502:physiology*; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006801:Humans; D008297:Male; D020325:Migraine with Aura / Q000503:physiopathology*; D020326:Migraine without Aura / Q000503:physiopathology*; D010775:Photic Stimulation; D011601:Psychophysics; D012160:Retina / Q000503:physiopathology; D012684:Sensory Thresholds / Q000502:physiology*; D014795:Visual Pathways / Q000503:physiopathology*; D055815:Young Adult