Glutamate is a neurotransmitter in the brain that plays a critical role in many brain functions, including learning, memory, and mood regulation. It is the primary excitatory neurotransmitter in the central nervous system. Glutamate receptors are proteins located on the surface of nerve cells (neurons) that respond to the binding of glutamate molecules, leading to various neuronal responses. There are several types of glutamate receptors, but two of the most well-known classes are NMDA receptors and AMPA receptors.