Magnesium plays an important role in relaying signals between your brain and body. It acts as the gatekeeper for the N-methyl-D-aspartate (NMDA) receptors, which are found on your nerve cells and aid brain development, memory and learning. In healthy adults, magnesium sits inside the NMDA receptors, preventing them from being triggered by weak signals that may stimulate your nerve cells unnecessarily. When your magnesium levels are low, fewer NMDA receptors are blocked. This means they are prone to being stimulated more often than necessary. This kind of overstimulation can kill nerve cells and may cause brain damage.