Correct Laminar Positioning in the Neocortex Influences Proper Dendritic and Synaptic Development

Fanny Sandrine Martineau (1) , Surajit Sahu , Vanessa Plantier (1) , Fabienne Schaller (1) , Lauriane Fournier , Geneviève Chazal (2) , Hiroshi Kawasaki (3) , Alfonso Represa (4, 1) , Francoise Watrin (1) , Jean-Bernard Manent (1)

1 INMED - INSERM U1249 - Institut de Neurobiologie de la Méditerranée [Aix-Marseille Université]
2 Développement et pathologie du motoneurone
3 Kagoshima University
4 Epilepsie et ischémie cérébrale

The neocortex is a 6-layered laminated structure with a precise anatomical and functional organization ensuring proper function. Laminar positioning of cortical neurons, as determined by termination of neuronal migration, is a key determinant of their ability to assemble into functional circuits. However, the exact contribution of laminar placement to dendrite morphogenesis and synapse formation remains unclear. Here we manipulated the laminar position of cortical neurons by knocking down doublecortin (Dcx), a crucial effector of migration, and show that misplaced neurons fail to properly form dendrites, spines, and functional glutamatergic and GABAergic synapses. We further show that knocking down Dcx in properly positioned neurons induces similar but milder defects, suggesting that the laminar misplacement is the primary cause of altered neuronal development. Thus, the specific laminar environment of their fated layers is crucial for the maturation of cortical neurons, and influences their functional integration into developing cortical circuits.

Keywords: circuit formation; cortical lamination; dendritogenesis; neocortex; synaptogenesis

Domains: Life Sciences [q-bio]; Neurons and Cognition [q-bio.NC]

Fanny Sandrine Martineau, Surajit Sahu, Vanessa Plantier, Fabienne Schaller, Lauriane Fournier, et al.. Correct Laminar Positioning in the Neocortex Influences Proper Dendritic and Synaptic Development. Cerebral Cortex, 2018, 28, pp.2976 - 2990. ⟨10.1093/cercor/bhy113⟩. ⟨hal-01962603⟩