Hippocampal Formation of Brain as Detector-Coder of Temporal Patterns of Information

The allocortical hippocampal formation, the isocortical cingulate gyrus, the amygdaloid nuclear complex, and the brain-stem ramifications of the fornix together form the main substance ofthe "limbic lobe" ofthe mammalian cerebral hemisphere. In recent years this complex has lost its claim to be called the "rhinencephalon," wholly concerned with the functions ofsmell, and has instead been variously deduced to be, in whole or in part, "a harmonious mechanism which may elaborate the functions of central emotion"; "a modulator of complex somatic, autonomic, and behavioral mechanisms integrated in subcortical structures"; "the visceral brain, concerned largely with mechanisms essential to preservation of the self and the species"; and "part of a broad positive motivational system." These descriptive conclusions affirm the common-sense expectation that, because it possesses the phylogenetically most invariant parts of the mammalian cortex, the limbic lobe probably contains the anatomical structures most proximately concerned with the innate and the learning mechanisms that operate the basic behavioral requirements of the mammal—-namely, species preservation through mating and rearing ofyoung and self-preservation through nutriton and countering of threats. The following preliminary, condensed presentation attempts to break through such laudable, but relatively superficial, structure-function identification to a deeper level of "causal explanation" in terms of specific microstructural "whats" and organizational "hows" (within a framework of non-teleological, ethological "whys"). It is the first sample airing of a comprehensive new interpretation ofall the constant morphological char-