Complex sentence: Since the initial discovery of the P300, research has shown that the P300 is not a unitary phenomenon-it, in fact, contains two distinguishable subcomponents: the novelty P3, or P3a, and the classic P300, which has since been renamed P3b.
Split into simpler sentences: Since the initial discovery of the P300, research has shown that the P300 has two subcomponents. The subcomponents are the novelty P3, or P3a, and the classic P300, which has since been renamed P3b.