ARTICLE Sir, In a recent publication in Brain, van den Berge et al. (2011) examined the brains of 10 controls, 10 patients with Parkinson’s disease, and five cases with incidental Lewy body disease and found no difference in the number of proliferating cells in the subventricular zone, thereby casting doubt on previously obtained evidence suggesting that central dopamine depletion impairs adult neuronal precursor cell proliferation. However, in this recent article the anatomical definition of the region of interest, the sampling procedure, some of the immunostaining procedures and the quantification methods were of limited precision and as such no firm conclusions can be drawn from this study about the dopamine regulation of subventricular zone neurogenesis in the human brain. The subventricular zone around the lateral ventricles in the adult mammalian brain harbours a specialized type of GFAP+ astrocytes, so-called B cells, which act as neural stem cells with the potential to self-renew and to give rise to astrocytes, oligodendrocytes and neurons (Doetsch et al., 1997). B cells generate frequently dividing transit-amplifying C cells. Division of C cells gives rise to A cells, a restricted type of neural precursor cells that can migrate to the olfactory bulb, where they mature into functional interneurons. The potential for neurogenesis is also conserved in the adult human subventricular zone (Sanai et al ., 2004), and as such this population of cells may be a potential resource for endogenous brain repair in brain disorders. To date, a comprehensive series of in vitro and in vivo experiments in adult rodents and non-human primates conducted by various independent research groups has provided compelling evidence that activation of dopamine receptors, mainly D2-type receptors, increases the proliferation of neural precursor cells, mainly C cells, in the subventricular zone (Baker et al., 2004; Coronas et al ., 2004; …