Research Highlight: Reallocation of Olfactory Cajal-Retzius Cells Shapes Neocortex Architecture

Our understanding of the mechanisms involved in the development of upper cortical association layers is limited. ENP team leader Sonia Garel and colleagues now show that, in mice, the density of a population of early-born transient glutamatergic neurons known as Cajal–Retzius cells (CRCs) in the Marginal Zone is essential to the proper development of the circuitery during necortical growth. The authors demonstrate that the pool of CRCs is properly maintained due to the migration of a reservoir of olfactory guidepost cells (lot cells) initially known for their role in axon guidance in the lateral olfactory tract. The authors show that lot cells possess all markers/functions of CRCs, and that their reallocation as a late remigrating pool of CRCs in the neocortex is modulated by the activity of NMDA receptors ex vivo. Importantly, reduction in CRCs density has a dramatic effect on the architecture of layer 1, known as a key region for cortical integration.

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Reallocation of Olfactory Cajal-Retzius Cells Shapes Neocortex Architecture. de Frutos CA, Bouvier G, Arai Y, Thion MS, Lokmane L, Keita M, Garcia-Dominguez M, Charnay P, Hirata T, Riethmacher D, Grove EA, Tissir F, Casado M, Pierani A, Garel S.   Neuron. 2016 Oct 19;92(2):435-448. doi: 10.1016/j.neuron.2016.09.020.

Figure: Slider neuron.