Faculté des sciences

An analysis of entorhinal cortex projections to the dentate gyrus, hippocampus, and subiculum of the neonatal macaque monkey

Amaral, David G. ; Kondo, Hideki ; Lavenex, Pierre

In: Journal of Comparative Neurology, 2013, p. -

The entorhinal cortex is the primary interface between the hippocampal formation and neocortical sources of sensory information. While much is known about the cells of origin, termination patterns and topography of the entorhinal projections to other fields of the adult hippocampal formation, very little is known about the development of these pathways, particularly in the human or nonhuman... Plus

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    Summary
    The entorhinal cortex is the primary interface between the hippocampal formation and neocortical sources of sensory information. While much is known about the cells of origin, termination patterns and topography of the entorhinal projections to other fields of the adult hippocampal formation, very little is known about the development of these pathways, particularly in the human or nonhuman primate. We have carried out experiments in which the anterograde tracers 3H-amino acids, biotinylated dextran amine and Phaseolus vulgaris leucoagglutinin were injected into the entorhinal cortex in 2-week-old rhesus monkeys (Macaca mulatta). We found that the three fiber bundles originating from the entorhinal cortex (the perforant path, the alvear pathway and the commissural connection) are all established by two weeks of age. Fundamental features of the laminar and topographic distribution of these pathways is also similar to those in adults. There is evidence, however, that some of these projections may be more extensive in the neonate than in the mature brain. The homotopic commissural projections from the entorhinal cortex, for example, originate from a larger region within the entorhinal cortex and terminate much more densely in layer I of the contralateral entorhinal cortex than in the adult. These findings indicate that the overall topographical organization of the main cortical afferent pathways to the dentate gyrus and hippocampus are established by birth. These findings add to the growing body of literature on the development of the primate hippocampal formation and will facilitate further investigations on the development of episodic memory.