Fig 2

Alternative models explaining the observed switch in the global expression profile sharply dividing prenatal and postnatal brain development. Patterns of expression of six hipothetical genes in two prenatal (S1, S2) and two postnatal (S3, S4) samples. a Switch in the global expression profile under constant regulatory interactions resulting from a pronounced change, during the perinatal boundary, in the overall level of expression of existing, but otherwise cohesive gene clusters. b A similar switch in the global expression profile resulting from a widespread remodelling of the underlying regulatory structure leading to the reassembly of new functional clusters. c Relatedness between actual coexpression profiles across anatomical regions. Gene coexpression matrices per cortical region were obtained for both prenatal and postnatal developmental windows. Unsupervised hierarchical clustering was conducted using pairwise correlations between all resulting coexpression matrices as a measure of similarity. Note that the coexpression structure of any two prenatal (or postnatal) regions are mores similar to each other, than they are to themselves across the perinatal boundary