INTERICTAL POTENTIATION OF PASSIVE ODDBALL AUDITORY EVENT-RELATED POTENTIALS IN MIGRAINE

We have studied habituation of the P3a component of the passive ''oddb all'' auditory event-related potential which reflects automatic proces sing of a ''novel'' stimulus in 24 patients suffering from migraine wi thout aura and in 21 healthy volunteers. Three blocks of responses to 160 standard and to 40 novel tones were sequentially averaged at Ct an d analyzed for latencies and peak-to-peak amplitudes. Latencies of com ponents N1 and P2 elicited by standard tones and of components N1, P2, N5 and P3a elicited by novel tones were not significantly different b etween sequential blocks or between subject groups, nor were mean N1-P 2 amplitudes. The N2-P3a amplitude tended to be lower in migraine, but not significantly so. The most striking result in migraineurs was a s ignificant potentiation of N2-P3a in successive blocks, contrasting wi th an habituation in controls. Our previous evoked- and event-related potential studies and the present one suggest that deficient habituati on, or even potentiation, represents interictally a fundamental dysfun ction of cortical information processing in migraine, which might incr ease energy demands and play a role in etiopathogenesis.