Region of cortex near to the rhinal sulcus. It is defined differently in different nomenclatures, due in part to the lack of agreement on the definition of the border of this region. In the rat, the perirhinal cortex occupies only caudal levels of the rhinal sulcus while in the monkey, it occurpies the full rostrocaudal extent of the rhinal sulcus (Burwell et al., Hippocampus, 5: 390-408, 1995). [ ]