The yin and yang of NMDA receptor signalling

Ca2+ entry through the NMDA subtype of glutamate receptors has the power to determine whether neurons survive or die. Too much NMDA receptor activity is harmful to neurons - but so is too little. Is it a case of too much or too little Ca2+ influx causing cell death or do other factors, such as receptor location or receptor-associated proteins, play a role? Understanding the mechanisms behind this dichotomous signalling is an important area of molecular neuroscience with direct clinical implications.