Synaptic physiology of excitatory amino acids

This paper gives a short overview of the localization of the main excitatory amino acid pathways in the mammalian brain and lists a few of the most important agonists and antagonists of the 5 excitatory acid receptors described to-date: the N-methyl-D-aspartate-(NMDA), a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid-(AMPA), kainic acid-, metabotropic- and presynaptic receptors. The main part summarizes work of this laboratory on excitatory amino acids involved in the synaptic physiology of the cortico-caudate, thalamo-cortical and a local cortical pathway studied in the cat brain in vivo. It concludes by presenting two hypotheses which describe how AMPA- and NMDA-receptors could interact in the brain to modulate synaptic function, the AMPA receptors being responsible for fast synaptic transmission while activation of NMDA-receptors enhance their gain either within a single synapse or from independent synapses or extrasynaptic sites.