Figure 4.

Building blocks for the three-layered cortex simulation. (A) Schematic representation of the desired cortex, with three layers L1, L2, and L3. Axonal projections are depicted by a black arrow, apical and basal dendrites are depicted in green. Note that L1 cells have no apical dendrite. (B) Gene regulatory network (black) and read-out genes (colored) producing the different neuronal types. The main motif is a pair of self exciting, mutually inhibiting genes. When sufficiently expressed, the gene a_i induces cell differentiation, whereas b_i allows the further division of the progenitors. Each pair is expressed sequentially. (C) Simulation snapshot of the three cell types. Identically colored segments are grown by instances of the same machine (black: axonal shaft, red: axonal ramification, light blue: apical dendritic shaft, violet: apical dendritic tuft, green: basal dendrite).