The N-methyl-D-aspartate receptor (also known as the NMDA receptor), is a glutamate receptor and ion channel protein found in nerve cells. It is activated when glutamate and glycine (or D-serine) bind to it, and when activated it allows positively charged ions to flow through the cell membrane.
How is our favorite mineral, Magnesium, involved? Thomas DeLauer (aka. "Mr. Mineral") explains.