The progresses in clarifying the normal and pathologic cellular and molecular mechanisms are reflected in the elucidation of the way some of the most common forms of generalized seizure--absence seizures--occur and are produced. Intrinsic properties of the thalamic neurons that give them the ability to release or preserve oscillatory, low-frequency neuronal discharges, and the thalamo-cortical feedback mechanism seem to explain the pathogenesis of absence seizures. The involvement of GABA receptors in the regulation of membrane calcium channels, as well as their genetically-induced changes are new pieces in the pathogenic puzzle.