PMC:4429232 / 11207-12851 JSONTXT

{"project":"0_colil","denotations":[{"id":"26029038-21701143-565809","span":{"begin":144,"end":148},"obj":"21701143"},{"id":"26029038-17533671-565810","span":{"begin":302,"end":306},"obj":"17533671"},{"id":"26029038-24105342-565811","span":{"begin":322,"end":326},"obj":"24105342"},{"id":"26029038-25417155-565812","span":{"begin":340,"end":344},"obj":"25417155"}],"text":"The specification of neocortical neurons depends on spatial patterning events delimiting the DP progenitors (Figure 1A; see for review Puelles, 2011), followed by temporal patterning mechanisms that lead these cells to sequentially produce the DL (first) and UL (last) (Figure 1C; Angevine and Sidman, 1961; Greig et al., 2013; Gao et al., 2014). When applying the above mentioned concepts to the evolution of the neocortical neurons, three main hypotheses can be drawn (Figure 1D): (1) Simple Expansion: DP progenitors of the reptilian ancestors produced homologous of both UL and DL neocortical neurons following the same temporal patterning mechanisms as in the modern neocortex. In this model the emergence of the neocortex was driven by changes only in the proliferation of DP progenitors and migration of their daughter cells. (2) Expansion and Segregation: gene modules underlying specific functions of UL and DL were present in a single precursor cell in the ancestral DP derivatives and became segregated and subsequently refined in distinct sister cell types. In this case the temporal patterning of DP progenitors will be a mammalian innovation. (3) Spatial to Temporal patterning switch: DP progenitors co-opted the expression of gene modules specifying the neuronal types of other pallial regions (i.e., MP, VP or LP), thus leading to the appearance of new cell types in the DP derivatives. The temporal patterning of neocortical progenitors may thus represent a patchwork of formerly spatially segregated developmental programs. In this case part of the neocortical cells may have a sister cell type in a different pallial domain."}

{"project":"2_test","denotations":[{"id":"26029038-21701143-38462715","span":{"begin":144,"end":148},"obj":"21701143"},{"id":"26029038-17533671-38462716","span":{"begin":302,"end":306},"obj":"17533671"},{"id":"26029038-24105342-38462717","span":{"begin":322,"end":326},"obj":"24105342"},{"id":"26029038-25417155-38462718","span":{"begin":340,"end":344},"obj":"25417155"}],"text":"The specification of neocortical neurons depends on spatial patterning events delimiting the DP progenitors (Figure 1A; see for review Puelles, 2011), followed by temporal patterning mechanisms that lead these cells to sequentially produce the DL (first) and UL (last) (Figure 1C; Angevine and Sidman, 1961; Greig et al., 2013; Gao et al., 2014). When applying the above mentioned concepts to the evolution of the neocortical neurons, three main hypotheses can be drawn (Figure 1D): (1) Simple Expansion: DP progenitors of the reptilian ancestors produced homologous of both UL and DL neocortical neurons following the same temporal patterning mechanisms as in the modern neocortex. In this model the emergence of the neocortex was driven by changes only in the proliferation of DP progenitors and migration of their daughter cells. (2) Expansion and Segregation: gene modules underlying specific functions of UL and DL were present in a single precursor cell in the ancestral DP derivatives and became segregated and subsequently refined in distinct sister cell types. In this case the temporal patterning of DP progenitors will be a mammalian innovation. (3) Spatial to Temporal patterning switch: DP progenitors co-opted the expression of gene modules specifying the neuronal types of other pallial regions (i.e., MP, VP or LP), thus leading to the appearance of new cell types in the DP derivatives. The temporal patterning of neocortical progenitors may thus represent a patchwork of formerly spatially segregated developmental programs. In this case part of the neocortical cells may have a sister cell type in a different pallial domain."}