Long term potentiation is the process of strengthening synapses based on patterns of activity or stimulation to the neuron. This process is believed to provide the foundation for a highly adaptable nervous system. Long term potentiation can be elicited by activating NMDA-type glutamate receptors, typically through the activity of pre and post-synaptic neurons. Depolarization and glutamate binding results in a calcium influx through NMDA receptors, which activates intracellular signaling cascades that ultimately are responsible for the altered synaptic efficacy.
It is proposed that this process is what allows us to make changes to the brain. While receptor activation has the potential to lead to long term potentiation and synaptogenesis, lack of stimulation can lead to the opposite— strengthening pathways while inhibiting others.