Neuroscience has long studied the impact of ionotropic glutamate receptors, such as AMPA and NMDA receptors, and their impacts in learning and memory. However, little is known of the role of metabotropic glutamate receptors and their impact in fundamental neurobiology. These 8 receptor subtypes are expressed in specific areas and neuronal cell types within the brain, thus understanding their physiology can help us understand function-specific biology and may elucidate what can happen when neuronal circuitry goes awry.