Active Networks in the Early Brain

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Science  13 Sep 2002:
Vol. 297, Issue 5588, pp. 1773
DOI: 10.1126/science.297.5588.1773a

Among the earliest neurons generated in the central nervous system are the Cajal-Retzius cells. Morphological studies suggest that they play an essential role in the structural and functional organization of the neocortex.

To examine these cells in more detail, Radnikow et al. investigated Cajal-Retzius cells in the developing rat neocortex to establish their input-output relations and synaptic physiology. The neurons are active elements in an early neuronal network, and receive heavy GABAergic and glutamatergic synaptic input. The glutamatergic input is purely NMDA receptor-mediated. The Cajal-Retzius cells possess very long (1000- to 2000-μ) horizontal axons that form asymmetric synaptic contacts with dendritic shafts or spines of neocortical pyramidal cells. The total population of these cells provides a dense axonal network that establishes synaptic contacts over a wide range of the cortical surface. Cajal-Retzius cells thus constitute an integrative element of an early cortical network, and the concerted action of Cajal-Retzius cell activity with their partner neurons may play an important role during the early stages of synaptic circuit development. — PRS

J. Neurosci.22, 6908 (2002).

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