Long term potentiation

Long term potentiation (LTP) is thought to result in learning and memory. Single action potentials fired in presynaptic cells aren't thought to have much of a long term affect. However, repeated firing of action potentials is believed to increase the quality and quantity of synaptic transmission. This process was initially noticed in the hippocampus, where some synapses display functional alterations with repeated use. The effect can vary in the length of time it stays around for, it can be from hours to weeks .

References

Alberts, Johnson, Lewis, Raff, Roberts, Walter (2008) Molecular Biology of the Cell, 5Th Edition, New York: Garland Science, Taylor and Francis group

Glutamate is the main exitatory transmitter in the central nervous system, and thus hwen it is released in the synapse, it binds to the AMPA, causing it to open and Na+ ions depolarise the post synaptic cell, increase in the depolarisation which is caused by increase in stimulation of the presynaptic neuronal cell, causes the Mg2+ to be removed from the nearby NMAD receptor and thus Ca2+ entr the cell and this in turn increases the cells sensitivity to glutamate.