Notes[N1] The term hippocampus is derived from the Greek words hippos (horse) and campus (sea monster). The brain region known as the hippocampus has the characteristic shape of a sea-horse's tail.

[N2] The hippocampus is a region of the brain crucial to memory formation and the lifelong production and integration of new nerve cells.

Corresponding AuthorLinda Richards, PhD, is an associate professor and the Head of Cortical Development and Axon Guidance at QBI. Dr. Richards' laboratory investigates how the brain becomes wired up during development, focusing on the development of the cerebral cortex, a region of the brain where all higher order cognition is processed.

CitationSpecific Glial Populations Regulate Hippocampal Morphogenesis. Guy Barry, Michael Piper, Charlotta Lindwall, Randal Moldrich, Sharon Mason, Erica Little, Anindita Sarkar, Shubha Tole, Richard M. Gronostajski, and Linda J. Richards1. Journal of Neuroscience 28(47): 12328 doi: 10.1523 / JNEUROSCI.4000-08.2008.

Abstract

The hippocampus plays an integral role in spatial navigation, learning and memory, and is a major site for adult neurogenesis. Critical to these functions is the proper organization of the hippocampus during development. Radial glia are known to regulate hippocampal formation, but their precise function in this process is yet to be defined. We find that in Nuclear Factor I b (Nfib)-deficient mice, a subpopulation of glia from the ammonic neuroepithelium of the hippocampus fail to develop. This results in severe morphological defects, including a failure of the hippocampal fissure, and subsequently the dentate gyrus, to form. As in wild-type mice, immature nestin-positive glia, which encompass all types of radial glia, populate the hippocampus in Nfib-deficient mice at embryonic day 15. However, these fail to mature into GLAST- and GFAP-positive glia, and the supragranular glial bundle is absent. In contrast, the fimbrial glial bundle forms, but alone is insufficient for proper hippocampal morphogenesis. Dentate granule neurons are present in the mutant hippocampus but their migration is aberrant, likely resulting from the lack of the complete radial glial scaffold usually provided by both glial bundles. These data demonstrate a role for Nfib in hippocampal fissure and dentate gyrus formation, and that distinct glial bundles are critical for correct hippocampal morphogenesis.