Finlay et al. describe a method of examining brain evolution, but it has limits that may hinder extrapolation to all vertebrate taxa or the understanding of how brains work. For example, members of different orders have brain and behavioral organization that are fundamentally different. Future investigations should incorporate a phylogenetic approach and more attention to behavior to further test their conclusions.

Recent studies of the contribution made by the hippocampus to spatial behavior suggest that it plays a role in integrating and double integrating distance and direction information using cues generated by self-movement. This and other evidence that the hippocampus plays a central role in spatial behavior seems inconsistent with proposals that it is primarily involved in episodic memory.