Explain the roles that the AMPA and NMDA receptors play in long-term potentiatio

Both AMPA and NMDA receptors are located on the postsynaptic cells (dendrites) and require binding of the excitatory neurotransmitter glutamate for activation. When glutamate binds to the AMPA receptor, the channel opens and Na enters the cell. This causes depolarization of the immediate postsynaptic cell or dendrite. This depolarization causes Mg2+ ions to be "kicked out" of the NMDA receptor channel; hence, Mg2+ is no longer acting as a channel blocker. If at the same time glutamate is bound to the NMDA receptor then the channel gate is open and Ca2+ enters the cell. The entry of Ca2+ triggers 2nd messenger pathways that results in an increase in the number of glutamate receptors inserted into the post-synaptic membrane. This increases the probability of an increase in the postsynaptic response or depolarization to glutamate that is referred to as long-term potentiation.