Long-range inhibitory mechanisms in the visual system are impaired in migraine sufferers.
BACKGROUND
After viewing dynamic noise surrounding a homogeneous grey patch (artificial scotoma), observers perceive a prolonged twinkling-noise after-image within the unstimulated area. It has been suggested that noise-stimulated neurons induce a long-range inhibition in neurons within the artificial scotoma, which generates a rebound signal perceived as twinkling noise following noise termination. We used this paradigm to test whether migraineurs have enhanced excitability or weakened inhibition.


METHODS
Twinkling-noise duration was measured in 13 headache-free volunteers, 13 migraineurs with aura and 13 migraineurs without aura.


RESULTS
The durations of the after-image were significantly shorter for both migraine groups compared to controls.


CONCLUSIONS
Enhanced excitation of noise-activated neurons in migraineurs would produce stronger rebound activity and longer after-image durations, while weakened inhibitory mechanisms would diminish the rebound activity and shorten the after-image durations compared to control subjects. The results suggest that cortical inhibitory mechanisms might be impaired in migraineurs with and without aura.
Department of Vision Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
Doreen
D
Wagner
Velitchko
V
Manahilov
Gael E
GE
Gordon
Peter
P
Storch
D000328:Adult; D000360:Afterimage / Q000502:physiology*; D015350:Contrast Sensitivity; D005260:Female; D006801:Humans; D008297:Male; D008564:Membrane Potentials; D020325:Migraine with Aura / Q000503:physiopathology*; D020326:Migraine without Aura / Q000503:physiopathology*; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation; D012607:Scotoma / Q000209:etiology / Q000503:physiopathology*; D014793:Visual Cortex / Q000503:physiopathology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult