N-methyl-D-aspartate (NMDA) is a specific type of receptor in the brain that plays a crucial role in synaptic plasticity, which is essential for learning and memory. It is activated by the neurotransmitter glutamate and requires the presence of glycine or D-serine to function properly. NMDA receptors are unique because they allow calcium ions to enter the neuron, which can trigger various cellular processes. These receptors are involved in many neurological functions and are also implicated in certain disorders, such as Alzheimer's disease and schizophrenia. Research on NMDA receptors has led to the development of drugs that target these receptors, aiming to improve cognitive function or alleviate symptoms associated with these conditions.