Final answer:
The largest input of the perforant pathway is from the entorhinal cortex, which carries information to the hippocampus for memory formation.
Step-by-step explanation:
The largest input of the perforant pathway is from the entorhinal cortex. The perforant pathway is a major neural pathway involved in memory and learning. It carries information from the entorhinal cortex to the hippocampus, which is important for forming new memories.