Neurogenesis and cortical surface

The size of the cortex depends to a large extent on the number of neural stem cells and their divisions prior to differentiation into neurons. The lecture therefore focused on the cellular and genetic mechanisms involved in amplifying the number of progenitors. This amplification is accompanied by the creation of an amplification compartment whose size peaks in sapiens and which is called the oSVZ for outside subventricular zone. An interesting example of the mechanisms involved is the ability of a long non-coding RNA (lncRNA) to complex, like a sponge, microRNAs whose action is to inhibit translation of a protein (Notch) that keeps progenitors in an undifferentiated proliferative state. As a result, expression of this lncRNA (lncND) increases the number of progenitors, as verified by in vivo electroporation in the mouse embryo. A second example discussed is that of TBC1D3, 17 copies of which are present in sapiens, versus one in chimpanzees, and whose expression in mice increases the size of the oSVZ and induces convolution formation.