Final answer:
Synaptic plasticity in the hippocampal formation is typically observed as Long-Term Potentiation (LTP), where synaptic connections are strengthened through increased AMPA receptor insertion due to calcium entry triggered by NMDA receptor activation.
Step-by-step explanation:
Synaptic plasticity in the hippocampal formation is typically observed as Long-Term Potentiation (LTP). LTP is a process where synaptic connections are persistently strengthened. This process is based on the Hebbian principle of 'cells that fire together wire together.' During LTP, multiple presynaptic inputs depolarize the postsynaptic neuron, displacing magnesium ions, which allows calcium ions to enter through NMDA receptors. This entry of calcium triggers a cascade that results in more AMPA receptors being inserted into the postsynaptic membrane. As a consequence, the synaptic connection becomes stronger, enhancing the excitatory postsynaptic potential (EPSP), thus making the postsynaptic neuron more likely to fire in response to presynaptic neurotransmitter release.