Answer
Eriugena did not directly study under Plotinus or Iamblichus, however he was influenced by their ideas. He was exposed to Neoplatonic thought through the works of other Christian thinkers, such as Augustine of Hippo and Dionysius the Pseudo-Areopagite. Eriugena's own work, On the Division of Nature, is heavily influenced by Neoplatonic thought, particularly the idea of the One and the Many.