AbstractRecent theories about migraine pathogenesis have outlined migraine as a brain disorder. Migraine can be considered an aberrant physiological state with a low threshold for intermittent neuronal excitability. Neurophysiologic findings in migraine emphasized the presence of abnormal neuronal function during the asymptomatic phase, predisposing to attack occurrence, the main patterns being the loss of habituation of evoked and event related potentials and the hypersynchronization of electroencephalographic (EEG) activity. These studies confirmed the need of preventive agents able to act on neuronal excitability, with growing evidence in favor of the clinical efficacy of anti‐epileptic drugs (AED), though electrophysiological evidence supporting migraine as a state of neuronal hypoexcitability rendered the rationale of their use and their fundamental action mechanism in preventing migraine rather questionable. In the last years, many studies reported the efficacy of other preventive agents than AED, such as ‐blockers, in reversing neurophysiologic abnormalities of migraine, while reducing headache frequency. Our recent results showed a normalizing effects of levetiracetam and topiramate vs. placebo on the dishabituation pattern of the contingent negative variation (CNV) and the efficacy of levetiracetam vs. both topiramate and placebo in reversing the hypersynchronization of alpha rhythm under flash stimulation. All these effects concurred with the clinical efficacy on migraine frequency, and confirmed the action of AED on the basal mechanisms of migraine. Considering our and previous results, migraine may be considered as a state of “altered” excitability, where the AED are modulating agents able to reverse the electrophysiological patterns predisposing to the attack occurrence. The challenge for the future may be the identification of subgroups of migraine patients with pronounced expression of some neurophysiologic indexes of migraine predisposition, e.g., hypersynchronization, which may optimize the choice of the preventive agent. Drug Dev Res 68:369–375, 2007. © 2007 Wiley‐Liss, Inc.