Brain Struct Funct (2011) 216:301–317 selective ablation of superﬁcial pyramidal cells with c- acetylenic GABA may help to deﬁne the functional importance of the two cell populations. The concept of a radial subdivision of the hippocampal pyramidal cell layer is rarely consciously considered in anatomical studies of the hippocampus, and it is, to our knowledge, not part of any computational model of hip- pocampal function. The understanding of neocortical function depends critically upon an understanding of laminar cortical organization with speciﬁc afferents ter- minating in speciﬁc layers, information being routed in speciﬁc ways between layers, efferent pathways origi- nating in speciﬁc layers, etc. An appreciation of a radial laminar organization within the classically identiﬁed subﬁelds of the hippocampus may contribute to our understanding of hippocampal function(s) to a similar extent. 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