Hippocampus & Behavior

Just as for the cerebellum, we decided to expose the postnatal hippocampus to X-rays to see what type of anatomical disruptions would result.  To our surprise, the hippocampus did not show any anatomical disruption (see photo at right).  The only effect was a moderate to profound reduction of cells in the dentate granular layer that depended on the number of X-ray exposures; the remaining granule cells were still in a recognizable granular layer.  We decided to put the hippocampal X-irradiated animals into behavioral tests that had been used on animals with large lesions of the hippocampus (see results from Bayer et al., 1973).  Here we made the amazing discovery that when approximately 85% of the dentate granule cells were depleted by the X-ray schedule, the animals behaved exactly as if the entire hippocampus had been lesioned.  Thus, whatever is the function of the hippocampus in the brain, the dentate granule cell population plays a critical role.
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application/pdf iconBayer et al nature 1973.pdf—-Behavioral and anatomical results of X-irradiation

application/pdf iconHaggbloom et al JCPP 1973.pdf—Behavior in X-irradiated animals

application/pdf iconBrunner et al PhysBehav 1974.pdf—Behavior in X-irradiated animals

application/pdf iconBayer&Peters Br Res Bull 2.pdf—Method used for X-irradiation

application/pdf iconGazzara&Altman JCPP 1981.pdf—Behavioral studies

application/pdf iconBayer&Altman Exp Neurol 48 1975.pdf—Anatomical quantitative studies of X-rayed animals

application/pdf iconMoore Zeigler&Bayer Exp Neurol 60.pdf—Monoamine innervation of X-rayed hippocampus

application/pdf iconWhishaw et al Br Res 146.pdf—Electrophysiology of X-rayed hippocampus