Final answer:
The ligand-gated ion channel that is excitatory and is the major binding site for phencyclidine is the NMDA receptors.
Step-by-step explanation:
The ligand-gated ion channel that is excitatory and is the major binding site for phencyclidine is the NMDA receptors. NMDA receptors are a type of glutamate receptor, which is the most prevalent excitatory neurotransmitter in the central nervous system. When glutamate binds to NMDA receptors, they allow the influx of calcium and sodium ions, which triggers intracellular events and contributes to synaptic plasticity and memory formation.