Ionotropic glutamate receptors are ligand-gated ion channels involved in fast excitatory transmission in the CNS. There are several types of glutamate ionotropic receptors including AMPA, kainate, and NMDA-receptor subunits. Most ionotropic glutamate receptors are located postsynaptically, although some are located presynaptically and on glia cells as well. Similar to the mGlu receptors, they are found throughout the brain including cortical regions, hippocampus, amygdala, basal ganglia, midbrain, hindbrain, and brainstem nuclei.