Influence of colors on habituation of visual evoked potentials in patientswith migraine with aura and in healthy volunteers

Objective.-To investigate whether colored glasses influence the habituation of visual evoked potentials. Background.-We have previously shown that during pattern-reversal stimulati ons lasting 2 minutes the amplitude of the visual evoked potential increase s in migraine with and without aura between attacks, whereas it decreases i n healthy volunteers. Red light was found to increase visually evoked EEG f ast activity only in children with migraine with aura. Wearing rose-tinted glasses for 3 months decreased attack frequency in parallel with a reductio n of the visually evoked EEG fast activity. Methods.-We compared the change in amplitude of the visual evoked potential using five different tinted glasses in 12 patients with migraine with aura and in 10 healthy volunteers. During continuous stimulation at 3.1 Hz, fiv e blocks of 50 responses were sequentially averaged using red, yellow, gree n, blue, and grey glasses and without glasses in a random order and analyze d in terms of latencies and N1-P1 amplitudes. Amplitude changes were calcul ated for each block by comparison with the first block in every condition a nd analyzed statistically using Zerbe's method. Results.-In healthy volunteers, the visual evoked potential amplitude incre ased with red glasses compared to without glasses (P=.05) or with green gla sses (P=.03). In patients with migraine with aura, no significant differenc e was detected using colored glasses. Our findings in healthy, volunteers a re in line with earlier reports of increased excitability of the human visu al cortex when exposed to red light. The lack of such a pattern in patients with migraine with aura suggests that the visual cortex is interictally hy poexcitable rather than hyperexcitable, which is consistent with studies of transcranial magnetic stimulation.