, 2010). Cortical

specification was suggested by Otx1 expression in approximately half of the cells and by mRNA detection for Foxg1 and Emx1. The differentiated cell population included Ctip2+ neurons; whether other glutamatergic subtypes were also produced was not addressed. The progenitor cell population was a heterogeneous mixture of cell types found throughout the rostrocaudal axis, given that mRNAs for midbrain and posterior CNS markers (En1, Hoxc5, and HB9), were also detected. Compared to the feeder-free telencephalic induction performed by Gaspard et al. (2008), it seems that the FGF2 and/or stromal click here cells may have interfered with the cells’ innate tendency to assume forebrain identity, consistent with the known caudalizing activity of FGF2 (Cox and Hemmati-Brivanlou, 1995, Koch et al., 2009 and Xu et al., 1997). Most intriguingly, however, the cells transplanted Alectinib purchase by Ideguchi et al. into various regions of the mouse cortex eventually extended axons to subcortical targets in a manner appropriate to their cortical site. This

targeting plasticity contrasted with the fixed targeting potential reported by Gaspard et al. (2008), who observed projections typical of visual cortex despite the cells being grafted into the frontal cortex. We will discuss this disparity later in the section on areal plasticity. Importantly, the low-density, adherent protocols for deriving cortical excitatory neurons have not yet been adapted for use with human ESCs or iPSCs. This will be a critical advance if the protocols are to become useful for understanding human cortical development and disease. The ability to study diseases of the cerebral cortex

in vitro and to develop cell-based therapies will below be greatly aided by the ability to produce specific neuronal subtypes from pluripotent stem cells. For example, ALS involves the degeneration of not only motor neurons in the spinal cord but also corticospinal motor neurons (CSMNs) in layer V of the motor cortex. To obtain a pure population of wild-type or disease-background CSMNs from pluripotent cell lines will require several steps: (1) direct pluripotent cells to a telencephalic fate; (2) direct telencephalic cells to a pallial fate; (3) direct pallial cells to the subregional fate of primordial motor cortex; and (4) direct motor cortex precursors to a deep laminar fate to generate and/or purify CSMNs and not other cortical projection neuron subtypes. Here, we review some of the mechanisms that generate various subtypes of cortical neurons from pluripotent stem cells, drawing on developmental studies. Given the default differentiation of pluripotent cells toward anterior neuroectoderm (Kamiya et al., 2011, Muñoz-Sanjuán and Brivanlou, 2002, Smukler et al.