These findings of early neurophysiological development in the parasubiculum
and presubiculum, spacial areas of the brain, underpin Haag's  concept of lateralization.
The hippocampus, however, is not a homogeneous structure but consists of several histologically and functionally distinct but tightly interconnected subfields: the subiculum with the subdivisions presubiculum, parasubiculum
, and subiculum proper; the four cornu ammonis sectors (CA1-4); and the dentate gyrus (DG) .
Redish and Touretzky (1997) have Suggested that the path integration is accomplished by an anatomical loop that includes the hippocampus, the subiculum, the parasubiculum
and the entorhinal cortex.