Enhanced glutamate synaptic transmission may be expected to alter the balance of excitation and inhibition in brain, leading to seizures. Several differences between epileptic and nonepileptic brains in presynaptic and postsynaptic glutamate mechanisms have been reported. These findings suggest that altered glutamate mechanisms contribute to the hyperexcitability of epileptic brain. For an expanded treatment of this topic see Jasper's Basic Mechanisms of the Epilepsies, Fourth Edition (Noebels JL, Avoli M, Rogawski MA, Olsen RW, Delgado-Escueta AV, eds) published by Oxford University Press (available on the National Library of Medicine Bookshelf [NCBI] at). © 2010 International League Against Epilepsy.