NG2 cells, oligodendrocyte progenitors, receive a major synaptic input from interneurons in the developing neocortex. It is presumed that these precursors integrate cortical networks where they act as sensors of neuronal activity. We show that NG2 cells of the developing somatosensory cortex form a transient and structured synaptic network with interneurons that follows its own rules of connectivity. Fast-spiking interneurons, highly connected to NG2 cells, target proximal subcellular domains containing GABAA receptors with γ2 subunits. Conversely, non-fast-spiking interneurons, poorly connected with these progenitors, target distal sites lacking this subunit. In the network, interneuron-NG2 cell connectivity maps exhibit a local spatial arrangement reflecting innervation only by nearest interneurons. This microcircuit architecture shows a connectivity peak at PN10, coinciding with a switch to massive oligodendrocyte differentiation. Hence, GABAergic innervation of NG2 cells is temporally and spatially regulated from the subcellular to the network level in coordination with the onset of oligodendrogenesis.
Animal experimentation: All experiments followed European Union and institutional guidelines for the care and use of laboratory of the INSERM. All of the animals were handled according to approved institutional animal care and use protocols of the University Paris Descartes. The protocol was approved by the Committee on the Ethics of Animal Experiments of the University Paris Descartes (Permit Number: CEEA34.MCA.070.12). Every effort was made to minimize suffering.
- Ben Barres, Stanford School of Medicine, United States
© 2015, Orduz et al.
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