title: Abnormal visual processing in migraine with aura: a study of steady-state visual evoked potentials.
abstract: BACKGROUND
  Although a number of studies reported different interictal findings between migraine with aura (MA) and migraine without aura (MO), the pathophysiology of the visual aura in migraine remains unclear.
  
  
  OBJECTIVE
  To investigate the visual processing in patients who experience MA between attacks using steady-state visual evoked potentials (SSVEPs).
  
  
  METHODS
  SSVEPs to high (98%) and low (29%) contrast black and white checkerboard gratings with two spatial frequencies (0.5 and 2.0 cpd) at 5 and 10 Hz (10 and 20 reversal/s) were recorded binocularly from 10 patients with MA, 10 patients with MO between attacks and 20 healthy controls (HC). The SSVEPs were Fourier analyzed to obtain the amplitude and phase of the second (2F) and fourth (4F) harmonic response.
  
  
  RESULTS
  In the amplitude of 2F, at 0.5 cpd, there was significant increased amplitude in both MA and MO in comparison to HC at 5 Hz in high and low contrast. However, no significant differences were detected at 2.0 cpd in both 5 and 10 Hz in high and low contrast. In the amplitude of 4F, at 2.0 cpd, there was significant increased amplitude in MA in comparison to MO and HC at 10 Hz in high contrast. However, there were no significant differences at 0.5 cpd at both 5 and 10 Hz in high and low contrast. There were no significant phase differences between MA, MO, and HC.
  
  
  CONCLUSIONS
  The high amplitude of the SSVEPs suggests that interictally migraine patients have abnormal excitability in the primary visual cortex, and this change in excitability may exist, at least partially, in the visual association cortex in MA.
authors.affiliation: Department of Medicine, Tokyo Women's Medical University, Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo, 116-8567, Japan. kshbtgm@dnh.twmu.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Shibata
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Yamane
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Otuka
authors.forename: Makoto
authors.initials: M
authors.lastname: Iwata
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015350:Contrast Sensitivity / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D020325:Migraine with Aura / Q000150:complications*; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D014786:Vision Disorders / Q000209:etiology*